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<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<meta name="dc.date" scheme="iso8601" content="2005-09-19" />
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<meta name="security" content="public" />
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<meta name="keywords" content="ALTER TABLE statement, ALTER TABLE,
SQL statements, altering, table, in ALTER TABLE statement, table-name,
ADD COLUMN clause, column-name, system-column-name, FOR COLUMN clause,
in ALTER TABLE, data-type, data type for ALTER TABLE, CCSID clause, CHAR,
DOUBLE PRECISION, DECIMAL, FLOAT, BIGINT, INTEGER, NUMERIC, REAL, SMALLINT,
VARCHAR, VARGRAPHIC, GRAPHIC, FOR BIT DATA clause, FOR MIXED DATA clause,
FOR SBCS DATA clause, BINARY, VARBINARY, BLOB, CLOB, DBCLOB, ROWID,
distinct-type, DEFAULT clause, constant, USER clause, NULL clause, CURRENT_DATE,
CURRENT_TIME, CURRENT_TIMESTAMP, cast-function, GENERATED, IDENTITY,
datalink-options, NOT NULL clause, CONSTRAINT clause, constraint-name,
PRIMARY KEY clause, UNIQUE clause, REFERENCES clause, CHECK clause,
ALTER COLUMN clause, SET DATA TYPE clause, SET default-clause,
SET NOT NULL clause, SET GENERATED ALWAYS clause,
SET GENERATED BY DEFAULT clause, DROP DEFAULT clause, DROP NOT NULL clause,
DROP IDENTITY clause, INCREMENT BY clause, MAXVALUE clause, MINVALUE clause,
NO CACHE clause, CACHE clause, NO ORDER clause, ORDER clause, NO CYCLE clause,
CYCLE clause, RESTART clause, DROP COLUMN clause,
in DROP COLUMN of ALTER TABLE statement, CASCADE clause, RESTRICT clause,
ADD unique-constraint clause, key, in ADD UNIQUE clause of ALTER TABLE statement,
in ADD PRIMARY clause of ALTER TABLE statement, of ALTER TABLE statement,
referential-constraint clause, in CONSTRAINT clause of ALTER TABLE statement,
FOREIGN KEY clause, in FOREIGN KEY clause of ALTER TABLE statement,
in REFERENCES clause of ALTER TABLE statement,
in ON DELETE clause of ALTER TABLE statement, DELETE clause, CASCADE delete rule,
RESTRICT delete rule, NO ACTION delete rule, SET DEFAULT delete rule,
SET NULL delete rule, keyword SET NULL delete rule, NULL,
in ON UPDATE clause of ALTER TABLE statement, UPDATE, RESTRICT update rule,
NO ACTION update rule, SET DEFAULT update rule, SET NULL update rule,
keyword SET NULL update rule, ADD check-constraint clause, check,
in CHECK clause of ALTER TABLE statement, check-condition,
DROP PRIMARY KEY clause, in DROP FOREIGN KEY clause of ALTER TABLE statement,
DROP FOREIGN KEY clause, in DROP UNIQUE clause of ALTER TABLE statement,
DROP UNIQUE clause, in DROP CHECK clause of ALTER TABLE statement,
DROP CHECK clause, in DROP CONSTRAINT clause of ALTER TABLE statement,
DROP CONSTRAINT clause, in DROP constraint of ALTER TABLE statement,
partitioning clause, DROP PARTITIONING, ADD PARTITION, partition name,
range partitions, hash partitions, ALTER PARTITION, DROP PARTITION, DELETE ROWS,
PRESERVE ROWS, ADD materialized query clause, materialized query table,
automatic summary table, ALTER materialized query clause,
DROP materialized query clause, ACTIVATE NOT LOGGED INITIALLY,
NOT LOGGED INITIALLY, WITH EMPTY TABLE, VOLATILE, NOT VOLATILE" />
<title>ALTER TABLE</title>
<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
<link rel="stylesheet" type="text/css" href="ic.css" />
</head>
<body>
<a id="Top_Of_Page" name="Top_Of_Page"></a><!-- Java sync-link -->
<script language = "Javascript" src = "../rzahg/synch.js" type="text/javascript"></script>
<a name="atabl"></a>
<h2 id="atabl"><a href="rbafzmst02.htm#ToC_762">ALTER TABLE</a></h2><a id="idx1331" name="idx1331"></a><a id="idx1332" name="idx1332"></a><a id="idx1333" name="idx1333"></a>
<a name="altabl"></a>
<p id="altabl">The ALTER TABLE statement alters the definition of a table.</p>
<a name="wq1065"></a>
<h3 id="wq1065"><a href="rbafzmst02.htm#ToC_763">Invocation</a></h3>
<p>This statement can be embedded in an application program or issued interactively.
It is an executable statement that can be dynamically prepared.</p>
<a name="wq1066"></a>
<h3 id="wq1066"><a href="rbafzmst02.htm#ToC_764">Authorization</a></h3>
<p>The privileges held by the authorization ID of the statement must include
at least one of the following: </p>
<ul>
<li>For the table identified in the statement,
<ul>
<li>The ALTER privilege on the table, and</li>
<li>The system authority *EXECUTE on the library containing the table</li></ul></li>
<li>Administrative authority</li></ul>
<p>To define a foreign key, the privileges held by the authorization ID of
the statement must include at least one of the following on the parent table: </p>
<ul>
<li>The REFERENCES privilege or object management authority for the table</li>
<li>The REFERENCES privilege on each column of the specified parent key</li>
<li>Ownership of the table</li>
<li>Administrative authority</li></ul>
<p>If a <var class="pv">select-statement</var> is specified, the privileges held by the
authorization ID of the statement must include at least one of the following
on the tables or views specified in these clauses: </p>
<ul>
<li>The SELECT privilege for the table or view</li>
<li>Ownership of the table or view</li>
<li>Administrative authority</li></ul>
<p>If a distinct type is referenced, the privileges held by the authorization ID of
the statement must include at least one of the following: </p>
<ul>
<li>For each distinct type identified in the statement:
<ul>
<li>The USAGE privilege on the distinct type, and</li>
<li>The system authority *EXECUTE on the library containing the distinct type</li></ul></li>
<li>Administrative authority</li></ul>
<p>For information on the system authorities corresponding to SQL privileges,
see <a href="rbafzmstgnt.htm#eqtablet">Corresponding System Authorities When Checking Privileges to a Table or View</a> and <a href="rbafzmstgntudtp.htm#eqtabled">Corresponding System Authorities When Checking Privileges to a Distinct Type</a>.</p>
<a name="wq1067"></a>
<h3 id="wq1067"><a href="rbafzmst02.htm#ToC_765">Syntax</a></h3>
<a href="rbafzmstatabl.htm#synsalter"><img src="c.gif" alt="Click to skip syntax diagram" /></a>
<a name="wq1068"></a>
<div class="fignone" id="wq1068">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn250.htm"
border="0" /></span><a href="#skipsyn-249"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>>>-ALTER TABLE--<span class="italic">table-name</span>-------------------------------------->
.-----------------------------------------------------------------------------.
V .-COLUMN-. |
>------+-ADD--+--------+--<span class="italic">column-definition</span>----------------------------------+---+->&lt;
| .-COLUMN-. |
+-ALTER--+--------+--<span class="italic">column-alteration</span>--------------------------------+
| .-COLUMN-. .-CASCADE--. |
+-DROP----+--------+--<span class="italic">column-name</span>--+----------+-----------------------+
| '-RESTRICT-' |
+-ADD--+-<span class="italic">unique-constraint</span>------+-------------------------------------+
| +-<span class="italic">referential-constraint</span>-+ |
| '-<span class="italic">check-constraint</span>-------' |
| .-CASCADE--. |
+-DROP--+-PRIMARY KEY----------------------+--+----------+------------+
| '-+-UNIQUE------+--<span class="italic">constraint-name</span>-' '-RESTRICT-' |
| +-FOREIGN KEY-+ |
| +-CHECK-------+ |
| '-CONSTRAINT--' |
+-ADD--<span class="italic">partitioning-clause</span>--------------------------------------------+
+-DROP PARTITIONING---------------------------------------------------+
+-ADD PARTITION--+-+----------------+--<span class="italic">boundary-spec</span>-+----------------+
| | '-<span class="italic">partition-name</span>-' | |
| '-<span class="italic">integer</span>--+-HASH PARTITIONS-+------' |
| '-HASH PARTITION--' |
+-ALTER PARTITION--<span class="italic">partition-name</span>--<span class="italic">boundary-spec</span>----------------------+
+-DROP PARTITION--<span class="italic">partition-name</span>--+-DELETE ROWS---+-------------------+
| '-PRESERVE ROWS-' |
| .-MATERIALIZED-. |
| .-+--------------+--QUERY-. |
+-ADD--+-------------------------+--<span class="italic">materialized-query-definition</span>-----+
| .-MATERIALIZED-. |
+-ALTER--+--------------+--QUERY--<span class="italic">materialized-query-table-alteration</span>-+
| .-MATERIALIZED-. |
+-DROP--+--------------+--QUERY---------------------------------------+
+-<span>ACTIVATE</span>--<span>NOT LOGGED INITIALLY</span>--+------------------+----------------+
| '-<span>WITH EMPTY TABLE</span>-' |
| .-<span>CARDINALITY</span>-. |
'-+-<span>NOT VOLATILE</span>-+--+-------------+-----------------------------------'
'-<span>VOLATILE</span>-----'
</pre>
<a name="skipsyn-249" id="skipsyn-249"></a></div>
<a name="wq1069"></a>
<div class="fignone" id="wq1069">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn251.htm"
border="0" /></span><a href="#skipsyn-250"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>column-definition:
|--<span class="italic">column-name</span>--+-------------------------------------+--------->
| .-COLUMN-. |
'-FOR--+--------+--<span class="italic">system-column-name</span>-'
>--<span class="italic">data-type</span>---------------------------------------------------->
.---------------------------------------------------------.
V | (3)
>----+-----------------------------------------------------+-+-------|
+-<span class="italic">default-clause</span>--------------------------------------+
| .-GENERATED ALWAYS-----. (1) |
+-+----------------------+-------+------------------+-+
| '-GENERATED BY DEFAULT-' '-<span class="italic">identity-options</span>-' |
| (2) |
+-<span class="italic">datalink-options</span>------------------------------------+
+-NOT NULL--------------------------------------------+
'-<span class="italic">column-constraint</span>-----------------------------------'
data-type:
|--+-<span class="italic">built-in-type</span>------+---------------------------------------|
'-<span class="italic">distinct-type-name</span>-'
</pre>
<a name="skipsyn-250" id="skipsyn-250"></a>
<a name="wq1070"></a>
<div class="notelisttitle" id="wq1070">Notes:</div>
<ol type="1">
<li>GENERATED can be specified only if the column has a ROWID data type
(or a distinct type that is based on a ROWID data type), or the column is
an identity column.</li>
<li>The datalink-options can only be specified for DATALINKs and distinct-types
sourced on DATALINKs.</li>
<li>The same clause must not be specified more than once.</li>
</ol></div>
<a name="wq1072"></a>
<div class="fignone" id="wq1072">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn252.htm"
border="0" /></span><a href="#skipsyn-251"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>built-in-type:
|--+-+---SMALLINT---+-------------------------------------------------------------------------------------------+--|
| +-+-INTEGER-+--+ |
| | '-INT-----' | |
| '---BIGINT-----' |
| .-(5,0)------------------------. |
+-+-+-DECIMAL-+-+--+------------------------------+----------------------------------------------------------+
| | '-DEC-----' | | .-,0--------. | |
| '-NUMERIC-----' '-(--<span class="italic">integer</span>--+-----------+--)-' |
| '-<span class="italic">, integer</span>-' |
| .-(--52--)------. |
+-+-FLOAT--+---------------+-+-------------------------------------------------------------------------------+
| | '-(--<span class="italic">integer</span>--)-' | |
| +-REAL---------------------+ |
| | .-PRECISION-. | |
| '-DOUBLE--+-----------+----' |
| .-(--1--)-------. |
+-+-+-+-CHARACTER-+--+---------------+-------------------------------+--+----------------+-----------------+-+
| | | '-CHAR------' '-(--<span class="italic">integer</span>--)-' | +-FOR BIT DATA---+ | |
| | '-+-+-CHARACTER-+--VARYING-+--(--<span class="italic">integer</span>--)--+-----------------+-' +-FOR SBCS DATA--+ | |
| | | '-CHAR------' | '-<span class="italic">allocate-clause</span>-' +-FOR MIXED DATA-+ | |
| | '-VARCHAR----------------' '-<span class="italic">ccsid-clause</span>---' | |
| | .-(--1M--)-------------. | |
| '---+-+-<span>CHARACTER</span>-+--<span>LARGE OBJECT</span>-+----+----------------------+--+-----------------+--+----------------+-' |
| | '-<span>CHAR</span>------' | '-(--<span class="italic">integer</span>--+---+--)-' '-<span class="italic">allocate-clause</span>-' +-FOR SBCS DATA--+ |
| '-<span>CLOB</span>------------------------' +-K-+ +-FOR MIXED DATA-+ |
| +-M-+ '-<span class="italic">ccsid-clause</span>---' |
| '-G-' |
| .-(--1--)-------. |
+-+---GRAPHIC----+---------------+----------------------------+--+--------------+----------------------------+
| | '-(--<span class="italic">integer</span>--)-' | '-<span class="italic">ccsid-clause</span>-' |
| +-+-GRAPHIC VARYING-+--(--<span class="italic">integer</span>--)--+-----------------+---+ |
| | '-VARGRAPHIC------' '-<span class="italic">allocate-clause</span>-' | |
| | .-(--1M--)-------------. | |
| '---DBCLOB----+----------------------+--+-----------------+-' |
| '-(--<span class="italic">integer</span>--+---+--)-' '-<span class="italic">allocate-clause</span>-' |
| +-K-+ |
| +-M-+ |
| '-G-' |
| .-(--1--)-------. |
+-+-+-BINARY--+---------------+------------------------------+-----------------+-----------------------------+
| | | '-(--<span class="italic">integer</span>--)-' | | |
| | '-+-BINARY VARYING-+--(--<span class="italic">integer</span>--)--+-----------------+-' | |
| | '-VARBINARY------' '-<span class="italic">allocate-clause</span>-' | |
| | .-(--1M--)-------------. | |
| '---+-BLOB----------------+----+----------------------+--+-----------------+-' |
| '-BINARY LARGE OBJECT-' '-(--<span class="italic">integer</span>--+---+--)-' '-<span class="italic">allocate-clause</span>-' |
| +-K-+ |
| +-M-+ |
| '-G-' |
+-+-DATE-------------------+---------------------------------------------------------------------------------+
| | .-(--0--)-. | |
| +-TIME--+---------+------+ |
| | .-(--6--)-. | |
| '-TIMESTAMP--+---------+-' |
| .-(--200--)-----. |
+---DATALINK--+---------------+--+-----------------+--+--------------+---------------------------------------+
| '-(--<span class="italic">integer</span>--)-' '-<span class="italic">allocate-clause</span>-' '-<span class="italic">ccsid-clause</span>-' |
'---ROWID----------------------------------------------------------------------------------------------------'
allocate-clause:
|--ALLOCATE--<span class="italic">(integer)</span>------------------------------------------|
ccsid-clause:
.-NOT NORMALIZED-.
|--CCSID--<span class="italic">integer</span>--+----------------+---------------------------|
'-NORMALIZED-----'
</pre>
<a name="skipsyn-251" id="skipsyn-251"></a></div>
<a name="wq1073"></a>
<div class="fignone" id="wq1073">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn253.htm"
border="0" /></span><a href="#skipsyn-252"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>default-clause:
.-WITH-.
|--+------+--DEFAULT--+-------------------------------------------------+--|
+-<span class="italic">constant</span>----------------------------------------+
+-USER--------------------------------------------+
+-NULL--------------------------------------------+
+-CURRENT_DATE------------------------------------+
+-CURRENT_TIME------------------------------------+
+-CURRENT_TIMESTAMP-------------------------------+
'-<span class="italic">cast-function-name</span>--(--+-<span class="italic">constant</span>----------+--)-'
+-USER--------------+
+-CURRENT_DATE------+
+-CURRENT_TIME------+
'-CURRENT_TIMESTAMP-'
identity-options:
|--AS IDENTITY--+-------------------------------------------------------+--|
| .-,-------------------------------------------. |
| V .-<span class="italic">1</span>----------------. (1) | |
'-(----+-START WITH--+-<span class="italic">numeric-constant</span>-+---+------+--)-'
| .-<span class="italic">1</span>----------------. |
+-INCREMENT BY--+-<span class="italic">numeric-constant</span>-+-+
| .-NO MINVALUE----------------. |
+-+-MINVALUE--<span class="italic">numeric-constant</span>-+-----+
| .-NO MAXVALUE----------------. |
+-+-MAXVALUE--<span class="italic">numeric-constant</span>-+-----+
| .-NO CYCLE-. |
+-+-CYCLE----+-----------------------+
| .-CACHE--<span class="italic">20</span>------. |
+-+-NO CACHE-------+-----------------+
| '-CACHE--<span class="italic">integer</span>-' |
| .-NO ORDER-. |
'-+-ORDER----+-----------------------'
column-constraint:
|--+-----------------------------+--+-+-PRIMARY KEY-+--------------+--|
'-CONSTRAINT--<span class="italic">constraint-name</span>-' | '-UNIQUE------' |
+-<span class="italic">references-clause</span>------------+
'-CHECK--(--<span class="italic">check-condition</span>--)-'
</pre>
<a name="skipsyn-252" id="skipsyn-252"></a>
<a name="wq1074"></a>
<div class="notelisttitle" id="wq1074">Notes:</div>
<ol type="1">
<li>The same clause must not be specified more than once.</li>
</ol></div>
<a name="wq1076"></a>
<div class="fignone" id="wq1076">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn254.htm"
border="0" /></span><a href="#skipsyn-253"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>datalink-options:
.-LINKTYPE URL-. .-NO LINK CONTROL--------------------------.
|--+--------------+--+------------------------------------------+--|
'-FILE LINK CONTROL--+-<span class="italic">file-link-options</span>-+-'
'-MODE DB2OPTIONS---'
file-link-options:
.---------------------------------------.
V (1) |
|----+-INTEGRITY ALL----------------+------+--------------------|
+-+-READ PERMISSION FS-+-------+
| '-READ PERMISSION DB-' |
+-+-WRITE PERMISSION FS------+-+
| '-WRITE PERMISSION BLOCKED-' |
+-RECOVERY NO------------------+
'-+-ON UNLINK RESTORE-+--------'
'-ON UNLINK DELETE--'
</pre>
<a name="skipsyn-253" id="skipsyn-253"></a>
<a name="wq1077"></a>
<div class="notelisttitle" id="wq1077">Notes:</div>
<ol type="1">
<li>All five <var class="pv">file-link-options</var> must be specified, but they can
be specified in any order.</li>
</ol></div>
<a name="wq1079"></a>
<div class="fignone" id="wq1079">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn255.htm"
border="0" /></span><a href="#skipsyn-254"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>column-alteration:
.-----------------------------------------------------------------------------------.
| .--------------------------------------------. |
V V (2) | |
|--<span class="italic">column-name</span>----+-SET--+----------------------+----+-+-<span class="italic">default-clause</span>----------------+-+------+-+-+--|
| '-DATA TYPE--<span class="italic">data-type</span>-' | | .-GENERATED ALWAYS-----. (1) | | |
| | '-+----------------------+------' | |
| | '-GENERATED BY DEFAULT-' | |
| '-NOT NULL--------------------------' |
| .-------------------. |
| V (2) | |
+-DROP----+-DEFAULT--+------+---------------------------------------------------+
| +-NOT NULL-+ |
| '-IDENTITY-' |
'-<span class="italic">identity-alteration</span>-----------------------------------------------------------'
identity-alteration:
.---------------------------------------------.
V | (2)
|----+-SET--+-INCREMENT BY--<span class="italic">numeric-constant</span>-+-+-+--------------|
| +-+-NO MINVALUE----------------+-+ |
| | '-MINVALUE--<span class="italic">numeric-constant</span>-' | |
| +-+-NO MAXVALUE----------------+-+ |
| | '-MAXVALUE--<span class="italic">numeric-constant</span>-' | |
| +-+-NO CYCLE-+-------------------+ |
| | '-CYCLE----' | |
| +-+-NO CACHE-------+-------------+ |
| | '-CACHE--<span class="italic">integer</span>-' | |
| '-+-NO ORDER-+-------------------' |
| '-ORDER----' |
'-RESTART--+------------------------+-----'
'-WITH--<span class="italic">numeric-constant</span>-'
</pre>
<a name="skipsyn-254" id="skipsyn-254"></a>
<a name="wq1080"></a>
<div class="notelisttitle" id="wq1080">Notes:</div>
<ol type="1">
<li>GENERATED can be specified only if the column has a ROWID data type
(or a distinct type that is based on a ROWID data type), or the column is
an identity column.</li>
<li>The same clause must not be specified more than once.</li>
</ol></div>
<a name="wq1082"></a>
<div class="fignone" id="wq1082">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn256.htm"
border="0" /></span><a href="#skipsyn-255"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>unique-constraint:
|--+-----------------------------+--+-PRIMARY KEY-+--(---------->
'-CONSTRAINT--<span class="italic">constraint-name</span>-' '-UNIQUE------'
.-,-----------.
V |
>----<span class="italic">column-name</span>-+--)-------------------------------------------|
referential-constraint:
|--+-----------------------------+--FOREIGN KEY----------------->
'-CONSTRAINT--<span class="italic">constraint-name</span>-'
.-,-----------.
V |
>--(----<span class="italic">column-name</span>-+--)--<span class="italic">references-clause</span>---------------------|
references-clause:
|--REFERENCES--<span class="italic">table-name</span>--+-----------------------+------------>
| .-,-----------. |
| V | |
'-(----<span class="italic">column-name</span>-+--)-'
.-ON DELETE NO ACTION--------. .-ON UPDATE NO ACTION-. (1)
>--+----------------------------+--+---------------------+-------|
'-ON DELETE--+-RESTRICT----+-' '-ON UPDATE RESTRICT--'
+-CASCADE-----+
+-SET NULL----+
'-SET DEFAULT-'
check-constraint:
|--+-----------------------------+------------------------------>
'-CONSTRAINT--<span class="italic">constraint-name</span>-'
>--CHECK--(--<span class="italic">check-condition</span>--)---------------------------------|
</pre>
<a name="skipsyn-255" id="skipsyn-255"></a>
<a name="wq1083"></a>
<div class="notelisttitle" id="wq1083">Notes:</div>
<ol type="1">
<li>The ON DELETE and ON UPDATE clauses may be specified in either order.</li>
</ol></div>
<a name="wq1085"></a>
<div class="fignone" id="wq1085">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn257.htm"
border="0" /></span><a href="#skipsyn-256"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>materialized-query-definition:
|--(--<span class="italic">select-statement</span>--)--<span class="italic">refreshable-table-options</span>------------|
refreshable-table-options:
.------------------------------------.
V | (1)
|--+-DATA INITIALLY DEFERRED--+--REFRESH DEFERRED----+-MAINTAINED BY USER-------------+-+-------|
'-DATA INITIALLY IMMEDIATE-' '-+-ENABLE QUERY OPTIMIZATION--+-'
'-DISABLE QUERY OPTIMIZATION-'
materialized-query-table-alteration:
|--+-(--<span class="italic">select-statement</span>--)--+---------------------------+-+----|
| '-<span class="italic">refreshable-table-options</span>-' |
| .------------------------------------. |
| V | (2) |
'-SET----+-REFRESH DEFERRED---------------+-+-----------'
+-MAINTAINED BY USER-------------+
'-+-ENABLE QUERY OPTIMIZATION--+-'
'-DISABLE QUERY OPTIMIZATION-'
</pre>
<a name="skipsyn-256" id="skipsyn-256"></a>
<a name="wq1086"></a>
<div class="notelisttitle" id="wq1086">Notes:</div>
<ol type="1">
<li>The same clause must not be specified more than once. MAINTAINED
BY USER must be specified.</li>
<li>The same clause must not be specified more than once.</li>
</ol></div>
<a name="wq1088"></a>
<div class="fignone" id="wq1088">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn258.htm"
border="0" /></span><a href="#skipsyn-257"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>partitioning-clause:
.-RANGE-.
|--PARTITION BY--+-+-------+--<span class="italic">range-partition-spec</span>-+------------|
'-HASH--<span class="italic">hash-partition-spec</span>-------'
range-partition-spec:
.-,----------------------------. .-,--------------------------------------------.
V .-NULLS LAST--. | V |
|--(----<span class="italic">column-name</span>--+-------------+-+--)--(--+---+---------------------------+--<span class="italic">boundary-spec</span>-+---------+--)--|
'-NULLS FIRST-' | '-PARTITION--<span class="italic">partition-name</span>-' |
'-<span class="italic">boundary-spec</span>--EVERY--(--<span class="italic">integer-constant</span>--+--------+--)-'
+-DAY----+
+-DAYS---+
+-MONTH--+
+-MONTHS-+
+-YEAR---+
'-YEARS--'
hash-partition-spec:
.-,-----------.
V |
|--(----<span class="italic">column-name</span>-+--)--INTO--<span class="italic">integer</span>--PARTITIONS-------------|
boundary-spec:
|--<span class="italic">starting-clause</span>--<span class="italic">ending-clause</span>-------------------------------|
starting-clause:
.-,------------.
.-FROM-. V | .-INCLUSIVE-.
|--STARTING--+------+--+-(----+-<span class="italic">constant</span>-+-+--)-+--+-----------+--|
| +-MINVALUE-+ | '-EXCLUSIVE-'
| '-MAXVALUE-' |
'-+-<span class="italic">constant</span>-+-----------'
+-MINVALUE-+
'-MAXVALUE-'
ending-clause:
.-,------------.
.-AT-. V | .-INCLUSIVE-.
|--ENDING--+----+--+-(----+-<span class="italic">constant</span>-+-+--)-+--+-----------+----|
| +-MINVALUE-+ | '-EXCLUSIVE-'
| '-MAXVALUE-' |
'-+-<span class="italic">constant</span>-+-----------'
+-MINVALUE-+
'-MAXVALUE-'
</pre>
<a name="skipsyn-257" id="skipsyn-257"></a></div>
<a name="synsalter"></a>
<h3 id="synsalter"><a href="rbafzmst02.htm#ToC_766">Description</a></h3>
<dl class="parml">
<dt class="bold"><var class="pv">table-name</var></dt>
<dd>Identifies the table you want to be altered. The <span class="italic">table-name</span> <a id="idx1334" name="idx1334"></a> must identify a table that exists at the current
server. It must not be a view, a catalog table, or a global temporary table.
If <span class="italic">table-name</span> identifies a materialized query table,
ADD <var class="pv">column-definition</var>, ALTER <var class="pv">column-alteration</var>, and DROP
COLUMN are not allowed.
</dd>
</dl>
<a name="wq1089"></a>
<h3 id="wq1089"><a href="rbafzmst02.htm#ToC_767">ADD COLUMN <span><var class="pv">column-definition</var></span></a></h3>
<p>Adds a column to the table. If the table has rows, every value of the column
is set to its default value, unless the column is a ROWID column or an identity
column (a column that is defined AS IDENTITY). The database manager generates default
values for ROWID columns and identity columns. If the table previously had <span class="italic">n</span> columns, the ordinality of the new column is <span class="italic">n</span>+1. The value of <span class="italic">n</span>+1 must not exceed 8000.</p><a id="idx1335" name="idx1335"></a>
<p>A table can have only one ROWID or identity column.</p>
<p>A DataLink column with FILE LINK CONTROL cannot be added to a table that
is a dependent in a referential constraint with a delete rule of CASCADE.</p>
<p>Adding a new column must not make the sum of the row buffer byte counts
of the columns be greater than 32766 or, if a VARCHAR or VARGRAPHIC column
is specified, 32740. Additionally, if a LOB is specified, the sum of the byte
counts of the columns must not be greater than 3 758 096 383 at the time of
insert or update. For information on the byte counts of columns according
to data type, see <a href="rbafzmsthctabl.htm#unctabl">Notes</a>.</p>
<dl class="parml">
<dt class="bold"><var class="pv">column-name</var> </dt><a id="idx1336" name="idx1336"></a>
<dd>Names the column to be added to the table. Do not use the same name
for more than one column of the table or for a system-column-name of the table.
Do not qualify <var class="pv">column-name</var>.
</dd>
<dt class="bold">FOR COLUMN <var class="pv">system-column-name</var> </dt><a id="idx1337" name="idx1337"></a><a id="idx1338" name="idx1338"></a>
<dd>Provides an i5/OS name for the column. Do not use the same name for
more than one column-name or system-column-name of the table.
<p>If the system-column-name
is not specified, and the column-name is not a valid system-column-name, a
system column name is generated. For more information about how system column
names are generated, see <a href="rbafzmsthctabl.htm#cnamrul">Rules for Column Name Generation</a>.</p>
</dd>
<dt class="bold"><var class="pv">data-type</var></dt><a id="idx1339" name="idx1339"></a><a id="idx1340" name="idx1340"></a><a id="idx1341" name="idx1341"></a><a id="idx1342" name="idx1342"></a><a id="idx1343" name="idx1343"></a><a id="idx1344" name="idx1344"></a><a id="idx1345" name="idx1345"></a><a id="idx1346" name="idx1346"></a><a id="idx1347" name="idx1347"></a><a id="idx1348" name="idx1348"></a><a id="idx1349" name="idx1349"></a><a id="idx1350" name="idx1350"></a><a id="idx1351" name="idx1351"></a><a id="idx1352" name="idx1352"></a><a id="idx1353" name="idx1353"></a><a id="idx1354" name="idx1354"></a><a id="idx1355" name="idx1355"></a><a id="idx1356" name="idx1356"></a><a id="idx1357" name="idx1357"></a><a id="idx1358" name="idx1358"></a><a id="idx1359" name="idx1359"></a><a id="idx1360" name="idx1360"></a><a id="idx1361" name="idx1361"></a><a id="idx1362" name="idx1362"></a>
<dd>Specifies the data type of the column. The data type can be a built-in
data type or a distinct type.
<dl class="parml">
<dt class="bold"><var class="pv">built-in-type</var> </dt><a id="idx1363" name="idx1363"></a>
<dd>Specifies a built-in data type. See <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a> for a description
of built-in types.
</dd>
<dt class="bold"><var class="pv">distinct-type-name</var></dt>
<dd>Specifies the data type of a column is a distinct type. The length, precision
and scale of the column are respectively the length, precision, and scale
of the source type of the distinct type. If a distinct type name is specified without a schema
name, the distinct type name is resolved by searching the schemas on the SQL path.
If the column is to be used in the definition of the foreign key of a referential
constraint, the data type of the corresponding column of the parent key must
have the same distinct type.
</dd>
</dl>
</dd>
<dt class="bold">DEFAULT </dt><a id="idx1364" name="idx1364"></a>
<dd>Specifies a default value for the column. This clause cannot be specified
more than once in the same <var class="pv">column-definition</var>. DEFAULT cannot be specified
for a ROWID column or an identity column (a column that is defined AS IDENTITY). The database manager generates
default values for ROWID columns and identity columns. If a value is not specified
following the DEFAULT keyword, then:
<ul>
<li>if the column is nullable, the default value is the null value.</li>
<li>if the column is not nullable, the default depends on the data type of
the column:
<dl>
<dt class="bold">Data type</dt>
<dd class="bold">Default value</dd>
<dt class="bold">Numeric</dt>
<dd>0
</dd>
<dt class="bold">Fixed-length character or graphic string</dt>
<dd>Blanks
</dd>
<dt class="bold">Fixed-length binary string</dt>
<dd>Hexadecimal zeros
</dd>
<dt class="bold">Varying-length string</dt>
<dd>A string length of 0
</dd>
<dt class="bold">Date</dt>
<dd>For existing rows, a date corresponding to 1 January 0001. For added
rows, the current date.
</dd>
<dt class="bold">Time</dt>
<dd>For existing rows, a time corresponding to 0 hours, 0 minutes, and 0
seconds. For added rows, the current time.
</dd>
<dt class="bold">Timestamp</dt>
<dd>For existing rows, a date corresponding to 1 January 0001 and a time
corresponding to 0 hours, 0 minutes, 0 seconds, and 0 microseconds. For added
rows, the current timestamp.
</dd>
<dt class="bold">Datalink</dt>
<dd>A value corresponding to DLVALUE('','URL','').
</dd>
<dt class="bold">Distinct type</dt>
<dd>The default value of the corresponding source type of the distinct type.
</dd>
</dl></li></ul>
<p>Omission of NOT NULL and DEFAULT from a <var class="pv">column-definition</var> is
an implicit specification of DEFAULT NULL. </p>
<dl class="parml">
<dt class="bold"><span class="italic">constant</span> </dt><a id="idx1365" name="idx1365"></a>
<dd>Specifies the constant as the default for the column. The specified
constant must represent a value that could be assigned to the column in accordance
with the rules of assignment as described in <a href="rbafzmstch2bas.htm#ch2bas">Assignments and comparisons</a>.
A floating-point constant must not be used for a SMALLINT, INTEGER, BIGINT,
DECIMAL, or NUMERIC column. A decimal constant must not contain more digits
to the right of the decimal point than the specified scale of the column.
</dd>
<dt class="bold"><span class="bold">USER</span></dt><a id="idx1366" name="idx1366"></a>
<dd>Specifies the value of the USER special register at the time of INSERT
or UPDATE as the default value for the column. The data type of the column
must be CHAR or VARCHAR with a length attribute that is greater than or equal
to the length attribute of the USER special register. For existing rows, the
value is that of the USER special register at the time the ALTER TABLE statement
is processed.
</dd>
<dt class="bold"><span class="bold">NULL</span> </dt><a id="idx1367" name="idx1367"></a>
<dd>Specifies null as the default for the column. If NOT NULL is specified,
DEFAULT NULL must not be specified within the same <var class="pv">column-definition</var>.
</dd>
<dt class="bold"><span class="bold">CURRENT_DATE</span> </dt><a id="idx1368" name="idx1368"></a>
<dd>Specifies the current date as the default for the column. If CURRENT_DATE
is specified, the data type of the column must be DATE or a distinct type
based on a DATE.
</dd>
<dt class="bold"><span class="bold">CURRENT_TIME</span> </dt><a id="idx1369" name="idx1369"></a>
<dd>Specifies the current time as the default for the column. If CURRENT_TIME
is specified, the data type of the column must be TIME or a distinct type
based on a TIME.
</dd>
<dt class="bold"><span class="bold">CURRENT_TIMESTAMP</span> </dt><a id="idx1370" name="idx1370"></a>
<dd>Specifies the current timestamp as the default for the column. If CURRENT_TIMESTAMP
is specified, the data type of the column must be TIMESTAMP or a distinct
type based on a TIMESTAMP.
</dd>
<dt class="bold"><span class="bold"><var class="pv">cast-function-name</var></span> <a id="idx1371" name="idx1371"></a></dt>
<dd>This form of a default value can only be used with columns defined as
a distinct type, <span>BINARY, VARBINARY,</span> BLOB, CLOB, DBCLOB, DATE, TIME,
or TIMESTAMP data types. The following table describes the allowed uses of
these <var class="pv">cast-functions</var>.
<a name="wq1090"></a>
<table id="wq1090" width="100%" summary="" border="1" frame="border" rules="none">
<thead valign="bottom">
<tr>
<th id="wq1091" width="47%" align="left" valign="top">Data Type</th>
<th id="wq1092" width="52%" align="left" valign="top">Cast Function Name</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq1091">Distinct type N based on a BINARY, VARBINARY,
BLOB, CLOB, or DBCLOB</td>
<td align="left" valign="top" headers="wq1092">BINARY, VARBINARY, BLOB, CLOB, or DBCLOB *</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1091">Distinct type N based on a DATE, TIME, or
TIMESTAMP</td>
<td align="left" valign="top" headers="wq1092">N (the user-defined cast function that was
generated when N was created) **
<div class="lines">or<br />
DATE, TIME, or TIMESTAMP *<br />
</div></td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1091">Distinct type N based on other data types</td>
<td align="left" valign="top" headers="wq1092">N (the user-defined cast function that was
generated when N was created) **</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1091">BINARY, VARBINARY, BLOB, CLOB, or DBCLOB</td>
<td align="left" valign="top" headers="wq1092">BINARY, VARBINARY, BLOB, CLOB, or DBCLOB *</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1091">DATE, TIME, or TIMESTAMP</td>
<td align="left" valign="top" headers="wq1092">DATE, TIME, or TIMESTAMP *</td>
</tr>
<tr>
<td colspan="2" align="left" valign="top" headers="wq1091 wq1092">
<a name="wq1093"></a>
<div class="notetitle" id="wq1093">Notes:</div>
<div class="notebody">
<p>* The name of the function must
match the name of the data type (or the source type of the distinct type)
with an implicit or explicit schema name of QSYS2.</p>
<p>**
The name of the function must match the name of the distinct type for the
column. If qualified with a schema name, it must be the same as the schema
name for the distinct type. If not qualified, the schema name from function
resolution must be the same as the schema name for the distinct type.</p></div></td>
</tr>
</tbody>
</table>
<dl class="parml">
<dt class="bold"><var class="pv">constant</var> </dt><a id="idx1372" name="idx1372"></a>
<dd>Specifies a constant as the argument. The constant must conform to the
rules of a constant for the source type of the distinct type or for the data
type if not a distinct type. For <span>BINARY, VARBINARY,</span> BLOB, CLOB, DBCLOB,
DATE, TIME, and TIMESTAMP functions, the constant must be a string constant.
</dd>
<dt class="bold"><span class="bold">USER</span></dt><a id="idx1373" name="idx1373"></a>
<dd>Specifies the value of the USER special register at the time of INSERT
or UPDATE as the default value for the column. The data type of the source
type of the distinct type of the column must be CHAR or VARCHAR with a length
attribute that is greater than or equal to the length attribute of USER. For
existing rows, the value is that of the USER special register at the time
the ALTER TABLE statement is processed.
</dd>
<dt class="bold"><span class="bold">CURRENT_DATE</span> </dt><a id="idx1374" name="idx1374"></a>
<dd>Specifies the current date as the default for the column. If CURRENT_DATE
is specified, the data type of the source type of the distinct type of the
column must be DATE.
</dd>
<dt class="bold"><span class="bold">CURRENT_TIME</span> </dt><a id="idx1375" name="idx1375"></a>
<dd>Specifies the current time as the default for the column. If CURRENT_TIME
is specified, the data type of the source type of the distinct type of the
column must be TIME.
</dd>
<dt class="bold"><span class="bold">CURRENT_TIMESTAMP</span> </dt><a id="idx1376" name="idx1376"></a>
<dd>Specifies the current timestamp as the default for the column. If CURRENT_TIMESTAMP
is specified, the data type of the source type of the distinct type of the
column must be TIMESTAMP.
</dd>
</dl>
</dd>
</dl>
<p>If the value specified is not valid, an error is returned.</p>
</dd>
<dt class="bold">GENERATED <a id="idx1377" name="idx1377"></a></dt>
<dd>Specifies that the database manager generates values for the column. GENERATED may
be specified if the column is to be considered an identity column (defined
with the AS IDENTITY clause). It may also be specified if the data type of
the column is a ROWID (or a distinct type that is based on a ROWID). Otherwise,
it must not be specified.
<dl class="parml">
<dt class="bold">ALWAYS</dt>
<dd>Specifies that the database manager will always generate a value for the column when
a row is inserted into the table. ALWAYS is the recommended value.
</dd>
<dt class="bold">BY DEFAULT</dt>
<dd>Specifies that the database manager will generate a value for the column when a row
is inserted only if a value is not specified for the column. If a value is
specified, the database manager uses that value.
<p>For a ROWID column, the database manager uses a
specified value, but it must be a valid unique row ID value that was previously
generated by DB2 UDB for z/OS or DB2 UDB for iSeries.</p>
<p>For an identity column, the database manager inserts
a specified value but does not verify that it is a unique value for the column
unless the identity column has a unique constraint or a unique index that
solely specifies the identity column.</p>
</dd>
</dl>
</dd>
<dt class="bold"><a id="idattr" name="idattr"></a>AS IDENTITY <a id="idx1378" name="idx1378"></a></dt>
<dd>Specifies that the column is an identity column for the table. A table
can have only one identity column. An identity column is not allowed in a <span>partitioned table or</span> distributed table. AS IDENTITY can be specified
only if the data type for the column is an exact numeric type with a scale
of zero (SMALLINT, INTEGER, BIGINT, DECIMAL or NUMERIC with a scale of zero,
or a distinct type based on one of these data types). If a DECIMAL or NUMERIC
data type is specified, the precision must not be greater than 31.
<p>An identity
column is implicitly NOT NULL. See the AS IDENTITY clause in <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a> for
the descriptions of the identity attributes.</p>
<p>A column in
a table cannot be altered to an identity column if the table is a DDS-created
physical file.</p>
</dd>
<dt class="bold"><var class="pv">datalink-options</var> <a id="idx1379" name="idx1379"></a></dt>
<dd>Specifies the options associated with a DATALINK column. See <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a> for
a description of <span class="italic">datalink-options</span>.
</dd>
<dt class="bold">NOT NULL </dt><a id="idx1380" name="idx1380"></a>
<dd>Prevents the column from containing null values. Omission of NOT NULL
implies that the column can contain null values. If NOT NULL is specified
in the column definition, then DEFAULT must also be specified.
</dd>
<dt class="bold"><var class="pv">column-constraint</var></dt>
<dd>The <var class="pv">column-constraint</var> of a <var class="pv">column-definition</var> provides
a shorthand method of defining a constraint composed of a single column.
Thus, if a <var class="pv">column-constraint</var> is specified in the definition of column
C, the effect is the same as if that constraint were specified as a <var class="pv">unique-constraint</var>, <var class="pv">referential-constraint</var> or <var class="pv">check-constraint</var> in which C is the only identified column.
<dl class="parml">
<dt class="bold"><span class="bold">CONSTRAINT</span> <var class="pv">constraint-name</var> <a id="idx1381" name="idx1381"></a><a id="idx1382" name="idx1382"></a></dt>
<dd>Names the constraint. A constraint-name must not identify a constraint
that already exists at the current server.
<p>If the clause is not specified,
a unique constraint name is generated by the database manager.</p>
</dd>
<dt class="bold"><span class="bold">PRIMARY KEY</span> </dt><a id="idx1383" name="idx1383"></a>
<dd>Provides a shorthand method of defining a primary key composed of a
single column. Thus, if PRIMARY KEY is specified in the definition of column
C, the effect is the same as if the PRIMARY KEY(C) clause is specified as
a separate clause.
<p>This clause must not be specified in more than one <var class="pv"> column-definition</var> and must not be specified at all if the UNIQUE clause
is specified in the column definition. The column must not be a LOB or DataLink
column.</p>
<p>When a primary key is added, a CHECK constraint is implicitly
added to enforce the rule that the NULL value is not allowed in the column
that makes up the primary key.</p>
</dd>
<dt class="bold"><span class="bold">UNIQUE</span> </dt><a id="idx1384" name="idx1384"></a>
<dd>Provides a shorthand method of defining a unique constraint composed
of a single column. Thus, if UNIQUE is specified in the definition of column
C, the effect is the same as if the UNIQUE (C) clause is specified as a separate
clause.
<p>This clause cannot be specified more than once in a column definition
and must not be specified if PRIMARY KEY is specified in the <var class="pv"> column-definition</var>. The column must not be a LOB or DataLink column.</p>
</dd>
<dt class="bold"><span class="italic">references-clause</span> <a id="idx1385" name="idx1385"></a></dt>
<dd>The <var class="pv">references-clause</var> of a column-definition provides a shorthand
method of defining a foreign key composed of a single column. Thus, if a <var class="pv">references-clause</var> is specified in the definition of column C, the effect
is the same as if that references-clause were specified as part of a FOREIGN
KEY clause in which C is the only identified column. A <var class="pv">references-clause</var> is not allowed if the table <span>is a global temporary table,
a partitioned table, or a distributed table.</span>
</dd>
<dt class="bold"><span class="bold">CHECK(</span><var class="pv">check-condition</var><span class="bold">)</span></dt><a id="idx1386" name="idx1386"></a>
<dd>Provides a shorthand method of defining a check constraint whose <var class="pv">check-condition</var> only references a single column. Thus, if CHECK is specified
in the column definition of column C, no columns other than C can be referenced
in the <var class="pv">check-condition</var> of the check constraint. The effect is the
same as if the check constraint were specified as a separate clause.
<p>ROWID
or DATALINK with FILE LINK CONTROL columns cannot be referenced in a CHECK
constraint. For additional restrictions see, <a href="rbafzmstatabl.htm#atcheckcst">ADD check-constraint</a>.</p>
</dd>
</dl>
</dd>
</dl>
<a name="wq1094"></a>
<h3 id="wq1094"><a href="rbafzmst02.htm#ToC_768">ALTER COLUMN <span><var class="pv">column-alteration</var></span></a></h3><a id="idx1387" name="idx1387"></a><a id="idx1388" name="idx1388"></a>
<p>Alters the definition of a column, including the attributes of an existing
identity column. Only the attributes specified will be altered. Others will
remain unchanged. </p>
<dl class="parml">
<dt class="bold"><var class="pv">column-name</var> </dt>
<dd>Identifies the column to be altered. The name must not be qualified
and must identify an existing column in the table. The name must not identify
a column that is being added or dropped in the same ALTER TABLE statement.
</dd>
<dt class="bold">SET DATA TYPE <var class="pv">data-type</var> </dt><a id="idx1389" name="idx1389"></a><a id="idx1390" name="idx1390"></a>
<dd>Specifies the new data type of the column to be altered.
The new data type must be compatible with the existing data type of the column.
For more information about the compatibility of data types see <a href="rbafzmstch2bas.htm#ch2bas">Assignments and comparisons</a>. However, changing a datetime data type to a character-string
data type or a numeric data type to a character-string data type or a character-string
data type to a numeric data type is not allowed.
<p>The specified length, precision,
and scale may be larger, smaller, or the same as the existing length, precision,
and scale. However, if the new length, precision, or scale is smaller, truncation
or numeric conversion errors may occur.</p>
<p>If the specified column has
a default value and a new default value is not specified, the existing default
value must represent a value that could be assigned to the column in accordance
with the rules for assignment as described in <a href="rbafzmstch2bas.htm#ch2bas">Assignments and comparisons</a>.</p>
<p>If the column is specified in a unique, primary, or foreign
key, the new sum of the lengths of the columns of the keys must not exceed
32766-<span class="italic">n</span>, where <span class="italic">n</span> is the number
of columns specified that allow nulls.</p>
<p>Changing the attributes will
cause any existing values in the column to be converted to the new column
attributes according to the rules for assignment to a column, except that
string values will be truncated.</p>
</dd>
<dt class="bold">SET <var class="pv">default-clause</var> </dt><a id="idx1391" name="idx1391"></a>
<dd>Specifies the new default value of the column to be altered. The specified
default value must represent a value that could be assigned to the column
in accordance with the rules for assignment as described in <a href="rbafzmstch2bas.htm#ch2bas">Assignments and comparisons</a>.
</dd>
<dt class="bold">SET NOT NULL </dt><a id="idx1392" name="idx1392"></a>
<dd>Specifies that the column cannot contain null values. All values for
this column in existing rows of the table must be not null. If the specified
column has a default value and a new default value is not specified, the existing
default value must not be NULL. SET NOT NULL is not allowed if the column
is identified in the foreign key of a referential constraint with a DELETE
rule of SET NULL and no other nullable columns exist in the foreign key.
</dd>
<dt class="bold">SET GENERATED ALWAYS or GENERATED BY DEFAULT</dt><a id="idx1393" name="idx1393"></a><a id="idx1394" name="idx1394"></a>
<dd>Specifies that the database manager generates values for the column. GENERATED may
be specified if the column is to be considered an identity column (defined
with the AS IDENTITY clause) or the data type of the column is a ROWID (or
a distinct type that is based on a ROWID). Otherwise, it must not be specified.
</dd>
<dt class="bold">DROP DEFAULT </dt><a id="idx1395" name="idx1395"></a>
<dd>Drops the current default for the column. The specified column must
have a default value and must not have NOT NULL as the null attribute. The
new default value is the null value.
</dd>
<dt class="bold">DROP NOT NULL </dt><a id="idx1396" name="idx1396"></a>
<dd>Drops the NOT NULL attribute of the column, allowing the column to have
the null value. If a default value is not specified or does not already exist,
the new default value is the null value. DROP NOT NULL is not allowed if the
column is specified in the primary key of the table or is an identity column
or ROWID.
</dd>
<dt class="bold">DROP IDENTITY </dt><a id="idx1397" name="idx1397"></a>
<dd>Drops the identity attributes of the column, making the column a simple
numeric data type column. DROP IDENTITY is not allowed if the column is not
an identity column.
</dd>
<dt class="bold"><var class="pv">identity-alteration</var></dt><a id="idx1398" name="idx1398"></a><a id="idx1399" name="idx1399"></a><a id="idx1400" name="idx1400"></a><a id="idx1401" name="idx1401"></a><a id="idx1402" name="idx1402"></a><a id="idx1403" name="idx1403"></a><a id="idx1404" name="idx1404"></a><a id="idx1405" name="idx1405"></a><a id="idx1406" name="idx1406"></a><a id="idx1407" name="idx1407"></a><a id="idx1408" name="idx1408"></a>
<dd>Alters the identity attributes of the column. The column must exist
in the specified table and must already be defined with the IDENTITY attribute.
For a description of the attributes, see <a href="rbafzmstatabl.htm#idattr">AS IDENTITY</a>.
<dl class="parml">
<dt class="bold">RESTART</dt>
<dd>Specifies the next value for an identity column. If WITH <var class="pv">numeric-constant</var> is not specified the sequence is restarted at the value specified implicitly
or explicitly as the starting value when the identity column was originally
created.
<dl class="parml">
<dt class="bold">WITH <var class="pv">numeric-constant</var></dt>
<dd>Specifies that <var class="pv">numeric-constant</var> will be used as
the next value for the column. The <var class="pv">numeric-constant</var> must be an exact
numeric constant that can be any positive or negative value that could be
assigned to this column, without nonzero digits existing to the right
of the decimal point.
</dd>
</dl>
</dd>
</dl>
</dd>
</dl>
<a name="wq1095"></a>
<h3 id="wq1095"><a href="rbafzmst02.htm#ToC_769">DROP COLUMN</a></h3><a id="idx1409" name="idx1409"></a>
<p>Drops the identified column from the table. </p>
<dl class="parml">
<dt class="bold"><var class="pv">column-name</var> </dt><a id="idx1410" name="idx1410"></a>
<dd>Identifies the column to be dropped. The column name must not be qualified.
The name must identify a column of the specified table. The name must not
identify a column that was already added or altered in this ALTER TABLE statement.
The name must not identify the only column of a table. The name must not identify
a partition key of a partitioned table or a distributed table.
</dd>
<dt class="bold">CASCADE </dt><a id="idx1411" name="idx1411"></a>
<dd>Specifies that any views, indexes, triggers, or constraints that are
dependent on the column being dropped are also dropped. <sup class="fn"><a href="rbafzmstatabl.htm#trgdep">55</a></sup>
</dd>
<dt class="bold">RESTRICT </dt><a id="idx1412" name="idx1412"></a>
<dd>Specifies that the column cannot be dropped if any views, indexes, triggers,
or constraints are dependent on the column. <sup class="fn"><a href="rbafzmstatabl.htm#trgdep">55</a></sup>
<p>If all the
columns referenced in a constraint are dropped in the same ALTER TABLE statement,
RESTRICT does not prevent the drop.</p>
</dd>
</dl>
<a name="wq1096"></a>
<h3 id="wq1096"><a href="rbafzmst02.htm#ToC_770">ADD unique-constraint</a></h3><a id="idx1413" name="idx1413"></a><a id="idx1414" name="idx1414"></a><a id="idx1415" name="idx1415"></a>
<dl class="parml">
<dt class="bold">CONSTRAINT <var class="pv">constraint-name</var></dt>
<dd>Names the constraint. A <var class="pv">constraint-name</var> must not identify a
constraint that already exists at the current server. The <var class="pv">constraint-name</var> must be unique within a schema.
<p>If not specified, a unique constraint
name is generated by the database manager.</p>
</dd>
<dt class="bold">UNIQUE (<var class="pv">column-name</var>,...) </dt><a id="idx1416" name="idx1416"></a><a id="idx1417" name="idx1417"></a><a id="idx1418" name="idx1418"></a>
<dd>Defines a unique constraint composed of the identified columns.
Each <var class="pv">column-name</var> must be an unqualified name that identifies a column
of the table. The same column must not be identified more than once. The column
must not be a LOB or DATALINK column. The number of identified columns must
not exceed 120, and the sum of their lengths must not exceed 32766-<span class="italic">n</span>, where <span class="italic">n</span> is the number of columns specified
that allow nulls.
<p>The set of identified columns cannot be the same as the
set of columns specified in another UNIQUE constraint or PRIMARY KEY on the
table. For example, UNIQUE (A,B) is not allowed if UNIQUE (B,A) or PRIMARY
KEY (A,B) already exists on the table. Any existing nonnull values in the
set of columns must be unique. Multiple null values are allowed.</p>
<p>If
a unique index already exists on the identified columns, that index is designated
as a unique constraint index. Otherwise, a unique index is created to support
the uniqueness of the unique key. The unique index is created as part of the
system physical file, not as a separate system logical file.</p>
</dd>
<dt class="bold">PRIMARY KEY (<var class="pv">column-name</var>,...) </dt><a id="idx1419" name="idx1419"></a><a id="idx1420" name="idx1420"></a><a id="idx1421" name="idx1421"></a>
<dd>Defines a primary key composed of the identified columns.
Each <var class="pv">column-name</var> must be an unqualified name that identifies a column
of the table. The same column must not be identified more than once. The column
must not be a LOB or DATALINK column. The number of identified columns must
not exceed 120, and the sum of their lengths must not exceed 32766. The table
must not already have a primary key.
<p>The identified columns cannot be the
same as the columns specified in another UNIQUE constraint on the table. For
example, PRIMARY KEY (A,B) is not allowed if UNIQUE (B,A) already exists on
the table. Any existing values in the set of columns must be unique.</p>
<p>When a primary key is added, a CHECK constraint is implicitly added to enforce
the rule that the NULL value is not allowed in any of the columns that make
up the primary key.</p>
<p>If a unique index already exists on the identified
columns, that index is designated as a primary index. Otherwise, a primary
index is created to support the uniqueness of the primary key. The unique
index is created as part of the system physical file, not a separate system
logical file.</p>
</dd>
</dl>
<a name="wq1097"></a>
<h3 id="wq1097"><a href="rbafzmst02.htm#ToC_771">ADD referential-constraint</a></h3><a id="idx1422" name="idx1422"></a><a id="idx1423" name="idx1423"></a><a id="idx1424" name="idx1424"></a>
<dl class="parml">
<dt class="bold">CONSTRAINT <var class="pv">constraint-name</var> </dt>
<dd>Names the constraint. A <var class="pv">constraint-name</var> must not identify a
constraint that already exists at the current server.
<p>If not specified,
a unique constraint name is generated by the database manager.</p>
</dd>
<dt class="bold">FOREIGN KEY</dt><a id="idx1425" name="idx1425"></a>
<dd>Defines a referential constraint. <span>FOREIGN KEY is not allowed if
the table is a partitioned table.</span>
<p>Let T1 denote the table being altered. </p>
<dl class="parml">
<dt class="bold">(<var class="pv">column-name</var>,...) </dt><a id="idx1426" name="idx1426"></a>
<dd>The foreign key of the referential constraint is composed
of the identified columns. Each <var class="pv">column-name</var> must be an unqualified
name that identifies a column of T1. The same column must not be identified
more than once. The column must not be a LOB or DATALINK column. The number
of the identified columns must not exceed 120, and the sum of their lengths
must not exceed 32766-<span class="italic">n</span>, where <span class="italic">n</span> is the number of columns specified that allows nulls.
</dd>
<dt class="bold">REFERENCES <var class="pv">table-name</var> </dt><a id="idx1427" name="idx1427"></a><a id="idx1428" name="idx1428"></a>
<dd>The <span class="italic">table-name</span> specified in a REFERENCES clause
must identify a base table that exists at the current server, but it <span>must not identify a catalog table, a global temporary table, a partitioned
table, or a distributed table.</span> This table is referred to as the parent
table in the constraint relationship.
<p>A referential constraint is a <var class="pv">duplicate</var> if its foreign key, parent key, and parent table are the same
as the foreign key, parent key, and parent table of an existing referential
constraint on the table. Duplicate referential constraints are allowed, but
not recommended.</p>
</dd>
</dl>
<p>Let T2 denote the identified parent table. </p>
<dl class="parml">
<dt class="bold">(<var class="pv">column-name,</var>...) </dt><a id="idx1429" name="idx1429"></a>
<dd>The parent key of the referential constraint is composed
of the identified columns. Each <var class="pv">column-name</var> must be an unqualified
name that identifies a column of T2. The same column must not be identified
more than once. The column must not be a LOB or DATALINK column. The number
of identified columns must not exceed 120, and the sum of their lengths must
not exceed 32766-<span class="italic">n</span>, where <span class="italic">n</span> is
the number of columns specified that allow nulls.
<p>The list of column names
must be identical to the list of column names in the primary key of T2 or
a UNIQUE constraint that exists on T2. The names may be specified in any order.
For example, if (A,B) is specified, a unique constraint defined as UNIQUE
(B,A) would satisfy the requirement. If a column name list is not specified
then T2 must have a primary key. Omission of the column name list is an implicit
specification of the columns of that primary key.</p>
<p>The specified foreign
key must have the same number of columns as the parent key of T2. The description
of the <span class="italic">n</span>th column of the foreign key and the <span class="italic">n</span>th column of the parent key must have identical data types, lengths,
and CCSIDs.</p>
</dd>
</dl>
<p>Unless the table is empty, the values of the foreign key must
be validated before the table can be used. Values of the foreign key are
validated during the execution of the ALTER TABLE statement. Therefore, every
nonnull value of the foreign key must match some value of the parent key of
T2.</p>
<p>The referential constraint specified by the FOREIGN KEY clause defines
a relationship in which T2 is the parent and T1 is the dependent. </p>
<dl class="parml">
<dt class="bold">ON DELETE </dt><a id="idx1430" name="idx1430"></a><a id="idx1431" name="idx1431"></a><a id="idx1432" name="idx1432"></a><a id="idx1433" name="idx1433"></a><a id="idx1434" name="idx1434"></a><a id="idx1435" name="idx1435"></a><a id="idx1436" name="idx1436"></a>
<dd>Specifies what action is to take place on the dependent tables when
a row of the parent table is deleted. There are five possible actions:
<ul>
<li>NO ACTION (default)</li>
<li>RESTRICT</li>
<li>CASCADE</li>
<li>SET NULL</li>
<li>SET DEFAULT</li></ul>
<p>SET NULL must not be specified unless some column of the foreign key
allows null values. SET NULL and SET DEFAULT must not be specified if T1
has an update trigger.</p>
<p>CASCADE must not be specified if T1 has a delete
trigger.</p>
<p>CASCADE must not be specified if T1 contains a DataLink column
with FILE LINK CONTROL.</p>
<p>The delete rule applies when a row of T2 is
the object of a DELETE or propagated delete operation and that row has dependents
in T1. Let <span class="italic">p</span> denote such a row of T2. </p>
<ul>
<li>If RESTRICT or NO ACTION is specified, an error occurs and no rows are
deleted.</li>
<li>If CASCADE is specified, the delete operation is propagated to the dependents
of <span class="italic">p</span> in T1.</li>
<li>If SET NULL is specified, each nullable column of the foreign key of each
dependent of <span class="italic">p</span> in T1 is set to null.</li>
<li>If SET DEFAULT is specified, each column of the foreign key of each dependent
of <span class="italic">p</span> in T1 is set to its default value.</li></ul>
</dd>
<dt class="bold">ON UPDATE </dt><a id="idx1437" name="idx1437"></a><a id="idx1438" name="idx1438"></a><a id="idx1439" name="idx1439"></a><a id="idx1440" name="idx1440"></a><a id="idx1441" name="idx1441"></a><a id="idx1442" name="idx1442"></a>
<dd>Specifies what action is to take place on the dependent tables when
a row of the parent table is updated.
<p>The update rule applies when a row
of T2 is the object of an UPDATE or propagated update operation and that row
has dependents in T1. Let <span class="italic">p</span> denote such a row of T2. </p>
<ul>
<li>If RESTRICT or NO ACTION is specified, an error occurs and no rows are
updated.</li></ul>
</dd>
</dl>
</dd>
</dl>
<a name="atcheckcst"></a>
<h3 id="atcheckcst"><a href="rbafzmst02.htm#ToC_772">ADD check-constraint</a></h3>
<dl class="parml"><a id="idx1443" name="idx1443"></a><a id="idx1444" name="idx1444"></a><a id="idx1445" name="idx1445"></a>
<dt class="bold">CONSTRAINT <var class="pv">constraint-name</var></dt>
<dd>Names the constraint. A <var class="pv">constraint-name</var> must not identify a
constraint that already exists at the current server. The <var class="pv">constraint-name</var> must be unique within a schema.
<p>If not specified, a unique constraint
name is generated by the database manager.</p>
</dd>
<dt class="bold">CHECK(<var class="pv">check-condition</var>)</dt><a id="idx1446" name="idx1446"></a><a id="idx1447" name="idx1447"></a><a id="idx1448" name="idx1448"></a>
<dd>Defines a check constraint. The <var class="pv">check-condition</var> must be true
or unknown for every row of the table.
<p>The <var class="pv">check-condition</var> is a <var class="pv">search-condition</var>, except:</p>
<ul>
<li>It can only refer to columns of the table and the column names must not
be qualified.</li>
<li>It cannot reference ROWID or DATALINK with FILE LINK CONTROL columns.</li>
<li>It must not contain any of the following:
<ul>
<li>Subqueries</li>
<li>Aggregate functions</li>
<li>Variables</li>
<li>Parameter markers</li>
<li>Complex expressions that contain LOBs (such as concatenation)</li>
<li>CURRENT DEBUG MODE, CURRENT DEGREE, CURRENT SCHEMA, CURRENT
SERVER, CURRENT PATH, SESSION_USER, SYSTEM_USER, and USER special registers</li>
<li>CURRENT DATE, CURRENT TIME, CURRENT TIMESTAMP, and CURRENT TIMEZONE special
registers</li>
<li>User-defined functions other than functions that were implicitly generated
with the creation of a distinct type</li>
<li>NOW, CURDATE, and CURTIME scalar functions</li>
<li>DBPARTITIONNAME scalar function</li>
<li>ATAN2, DIFFERENCE, RAND, RADIANS, and SOUNDEX scalar functions</li>
<li>DLVALUE, DLURLPATH, DLURLPATHONLY, DLURLSERVER, or DLURLSCHEME scalar
functions</li>
<li>DLURLCOMPLETE scalar function (for DataLinks with an attribute of FILE
LINK CONTROL and READ PERMISSION DB)</li>
<li>DECRYPT_BIT, DECRYPT_BINARY, DECRYPT_CHAR, DECRYPT_DB, ENCRYPT_RC2,
ENCRYPT_TDES, and GETHINT</li>
<li>DAYNAME, MONTHNAME, NEXT_DAY, and VARCHAR_FORMAT</li>
<li>INSERT, REPEAT, and REPLACE</li>
<li>GENERATE_UNIQUE and RAISE_ERROR</li></ul></li></ul>
</dd>
</dl>
<p>For more information about search-condition, see <a href="rbafzmstch2srch.htm#ch2srch">Search conditions</a>.</p>
<a name="wq1098"></a>
<h3 id="wq1098"><a href="rbafzmst02.htm#ToC_773">DROP</a></h3>
<dl class="parml">
<dt class="bold">PRIMARY KEY </dt><a id="idx1449" name="idx1449"></a>
<dd>Drops the definition of the primary key and all referential constraints
in which the primary key is a parent key. The table must have a primary key.
</dd>
<dt class="bold">FOREIGN KEY <var class="pv">constraint-name</var> </dt><a id="idx1450" name="idx1450"></a><a id="idx1451" name="idx1451"></a>
<dd>Drops the referential constraint <var class="pv">constraint-name</var>. The <var class="pv">constraint-name</var> must identify a referential constraint in which the table
is a dependent.
</dd>
<dt class="bold">UNIQUE <var class="pv">constraint-name</var> </dt><a id="idx1452" name="idx1452"></a><a id="idx1453" name="idx1453"></a>
<dd>Drops the unique constraint <span class="italic">constraint-name</span> and
all referential constraints dependent on this unique constraint. The <span class="italic">constraint-name</span> must identify a unique constraint on the table. DROP
UNIQUE will not drop a PRIMARY KEY unique constraint.
</dd>
<dt class="bold">CHECK <var class="pv">constraint-name</var></dt><a id="idx1454" name="idx1454"></a><a id="idx1455" name="idx1455"></a>
<dd>Drops the check constraint <span class="italic">constraint-name</span>.
The <var class="pv">constraint-name</var> must identify a check constraint
on the table.
</dd>
<dt class="bold">CONSTRAINT <var class="pv">constraint-name</var> </dt><a id="idx1456" name="idx1456"></a><a id="idx1457" name="idx1457"></a>
<dd>Drops the constraint <var class="pv">constraint-name</var>. The <var class="pv">constraint-name</var> must identify a unique, referential, or check constraint on the table.
If the constraint is a PRIMARY KEY or UNIQUE constraint, all referential constraints
in which the primary key or unique key is a parent are also dropped.
</dd>
<dt class="bold">CASCADE </dt><a id="idx1458" name="idx1458"></a>
<dd>Specifies for unique constraints that any referential constraints that
are dependent on the constraint being dropped are also dropped.
</dd>
<dt class="bold">RESTRICT </dt><a id="idx1459" name="idx1459"></a>
<dd>Specifies for unique constraints that the constraint cannot be dropped
if any referential constraints are dependent on the constraint.
</dd>
</dl>
<a name="wq1099"></a>
<h3 id="wq1099"><a href="rbafzmst02.htm#ToC_774">ADD partitioning-clause</a></h3><a id="idx1460" name="idx1460"></a>
<p>Changes a non-partitioned table into a partitioned table. If
the specified table is a distributed table or already a partitioned table,
an error is returned. A table with an identity column cannot be partitioned.
A DDS-created physical file cannot be partitioned. See <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a> for
a description of the <var class="pv">partitioning-clause</var>.</p>
<p>Changing a non-partitioned table that contains data into a partitioned
table will require data movement between the data partitions. When using range
partitioning, all existing data in the table must be assignable to the specified
range partitions.</p>
<a name="wq1100"></a>
<h3 id="wq1100"><a href="rbafzmst02.htm#ToC_775">DROP PARTITIONING</a></h3><a id="idx1461" name="idx1461"></a>
<p>Changes a partitioned table into a non-partitioned table. If the specified
table is already non-partitioned, an error is returned.</p>
<p>Changing a partitioned table that contains data into a non-partitioned
table will require data movement between the data partitions.</p>
<a name="wq1101"></a>
<h3 id="wq1101"><a href="rbafzmst02.htm#ToC_776">ADD PARTITION</a></h3><a id="idx1462" name="idx1462"></a>
<p>Adds one or more partitions to a partitioned table. If the specified table
is not a partitioned table, an error is returned. The number of partitions
must not exceed 256.</p>
<p>Changing the number of hash partitions in a partitioned table that contains
data will require data movement between the data partitions.</p>
<p></p>
<dl class="parml">
<dt class="bold"><var class="pv">partition-name</var></dt><a id="idx1463" name="idx1463"></a>
<dd>Names the partition. A <var class="pv">partition-name</var> must not identify a data
partition that already exists in the table.
<p>If the clause is not specified,
a unique partition name is generated by the database manager.</p>
</dd>
<dt class="bold"><var class="pv">boundary-spec</var> </dt><a id="idx1464" name="idx1464"></a>
<dd>Specifies the boundaries of a range partition. If the specified table
is not a range partitioned table, an error is returned. See <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a> for
a description of the <var class="pv">boundary-spec</var>.
</dd>
</dl>
<p></p>
<dl class="parml">
<dt class="bold"><var class="pv">integer</var> HASH PARTITIONS</dt><a id="idx1465" name="idx1465"></a>
<dd>Specifies the number of hash partitions to be added. If the specified
table is not a hash partitioned table, an error is returned.
</dd>
</dl>
<a name="wq1102"></a>
<h3 id="wq1102"><a href="rbafzmst02.htm#ToC_777">ALTER PARTITION</a></h3><a id="idx1466" name="idx1466"></a>
<p>Alters the boundaries of a partition of a range partitioned table. If the
specified table is not a range partitioned table, an error is returned.</p>
<p>Changing the boundaries of one or more partitions of a table that contains
data may require data movement between the data partitions. All existing data
in the table must be assignable to the specified range partitions.</p>
<dl class="parml">
<dt class="bold"><var class="pv">partition-name</var></dt><a id="idx1467" name="idx1467"></a>
<dd>Specifies the name of the partition to alter. The <var class="pv">partition-name</var> must identify a data partition that exists in the table.
</dd>
<dt class="bold"><var class="pv">boundary-spec</var> </dt><a id="idx1468" name="idx1468"></a>
<dd>Specifies the new boundaries of a range partition. See <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a> for
a description of the <var class="pv">boundary-spec</var>.
</dd>
</dl>
<a name="wq1103"></a>
<h3 id="wq1103"><a href="rbafzmst02.htm#ToC_778">DROP PARTITION</a></h3><a id="idx1469" name="idx1469"></a>
<p>Drops a partition of a partitioned table. If the specified table is not
a partitioned table, an error is returned. If the last remaining partition
of a partitioned table is specified, an error is returned.</p>
<p></p>
<dl class="parml">
<dt class="bold"><var class="pv">partition-name</var></dt><a id="idx1470" name="idx1470"></a>
<dd>Specifies the name of the partition to drop. The <var class="pv">partition-name</var> must identify a data partition that exists in the table.
</dd>
<dt class="bold">DELETE ROWS</dt><a id="idx1471" name="idx1471"></a>
<dd>Specifies that any data in the specified partition will be discarded.
All data stored in the partition is dropped from the table without processing
any delete triggers.
</dd>
<dt class="bold">PRESERVE ROWS</dt><a id="idx1472" name="idx1472"></a>
<dd>Specifies that any data in the specified partition will be preserved
by moving it to the remaining partitions without processing any delete or
insert triggers. If the specified table is a range partitioned table, PRESERVE
ROWS must not be specified. Dropping a hash partition will require data movement
between the remaining data partitions.
</dd>
</dl>
<a name="wq1104"></a>
<h3 id="wq1104"><a href="rbafzmst02.htm#ToC_779">ADD MATERIALIZED QUERY materialized-query-definition</a></h3><a id="idx1473" name="idx1473"></a>
<p>Changes a base table to a materialized query table. If the specified table
is already a materialized query table or if the table is referenced in another
materialized query table, an error is returned. </p>
<dl class="parml">
<dt class="bold"><var class="pv">select-statement</var> </dt>
<dd>Defines the query on which the table is based. The columns of the existing
table must meet the following characteristics:
<ul>
<li>The number of columns in the table must be the same as the number of result
columns in the <var class="pv">select-statement</var>.</li>
<li>The column attributes of each column of the table must be compatible to
the column attributes of the corresponding result column in the <var class="pv">select-statement</var>.</li></ul>
<p>The <var class="pv">select-statement</var> for a materialized query table must
not contain a reference to the table being altered, a view over the table
being altered, or another materialized query table. For additional details
about specifying <var class="pv">select-statement</var> for a materialized query table,
see <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a>.</p>
</dd>
<dt class="bold">refreshable-table-options</dt><a id="idx1474" name="idx1474"></a><a id="idx1475" name="idx1475"></a>
<dd>Specifies the materialized query table options for altering a base table
to a materialized query table.
<dl class="parml">
<dt class="bold">DATA INITIALLY DEFERRED</dt>
<dd>Specifies that the data in the table is not validated as part of the
ALTER TABLE statement. A REFRESH TABLE statement can be used to make sure
the data in the materialized query table is the same as the result of the
query in which the table is based.
</dd>
<dt class="bold">DATA INITIALLY IMMEDIATE</dt>
<dd>Specifies that the data is inserted in the table from the result of
the query as part of processing the ALTER TABLE statement.
</dd>
<dt class="bold">REFRESH DEFERRED</dt>
<dd>Specifies that the data in the table can be refreshed at any time using
the REFRESH TABLE statement. The data in the table only reflects the result
of the query as a snapshot at the time when the REFRESH TABLE statement is
processed or when it was last updated.
</dd>
<dt class="bold">MAINTAINED BY USER</dt>
<dd>Specifies that the materialized query table is maintained by the user.
The user can use INSERT, DELETE, UPDATE, or REFRESH TABLE statements on the
table.
</dd>
<dt class="bold">ENABLE QUERY OPTIMIZATION</dt>
<dd>Specifies that the materialized query table can be used for
query optimization.
</dd>
<dt class="bold">DISABLE QUERY OPTIMIZATION</dt>
<dd>Specifies that the materialized query table cannot be used for query
optimization. The table can still be queried directly.
</dd>
</dl>
</dd>
</dl>
<a name="wq1105"></a>
<h3 id="wq1105"><a href="rbafzmst02.htm#ToC_780">ALTER MATERIALIZED QUERY materialized-query-table-alteration</a></h3><a id="idx1476" name="idx1476"></a>
<p>Changes the attributes of a materialized query table. The <var class="pv">table-name</var> must identify a materialized query table.</p>
<dl class="parml">
<dt class="bold"><var class="pv">select-statement</var> </dt>
<dd>Defines the query on which the table is based. The columns of the existing
table must meet the following characteristics:
<ul>
<li>The number of columns in the table must be the same as the number of result
columns in the <var class="pv">select-statement</var>.</li>
<li>The column attributes of each column of the table must be compatible to
the column attributes of the corresponding result column in the <var class="pv">select-statement</var>.</li></ul>
<p>The <var class="pv">select-statement</var> for a materialized query table must
not contain a reference to the table being altered, a view over the table
being altered, or another materialized query table. For additional details
about specifying <var class="pv">select-statement</var> for a materialized query table,
see <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a>.</p>
</dd>
<dt class="bold"><var class="pv">refreshable-table-options</var></dt><a id="idx1477" name="idx1477"></a><a id="idx1478" name="idx1478"></a>
<dd>Specifies the materialized query table options for altering a base table
to a materialized query table.
<dl class="parml">
<dt class="bold">DATA INITIALLY DEFERRED</dt>
<dd>Specifies that the data in the table is not refreshed or validated as
part of the ALTER TABLE statement. A REFRESH TABLE statement can be used to
make sure the data in the materialized query table is the same as the result
of the query in which the table is based.
</dd>
<dt class="bold">DATA INITIALLY IMMEDIATE</dt>
<dd>Specifies that the data is inserted in the table from the result of
the query as part of processing the ALTER TABLE statement.
</dd>
<dt class="bold">REFRESH DEFERRED</dt>
<dd>Specifies that the data in the table can be refreshed at any time using
the REFRESH TABLE statement. The data in the table only reflects the result
of the query as a snapshot at the time when the REFRESH TABLE statement is
processed or when it was last updated.
</dd>
<dt class="bold">MAINTAINED BY USER</dt>
<dd>Specifies that the materialized query table is maintained by the user.
The user can use INSERT, DELETE, UPDATE, or REFRESH TABLE statements on the
table.
</dd>
<dt class="bold">ENABLE QUERY OPTIMIZATION <span class="base">or</span> DISABLE
QUERY OPTIMIZATION</dt>
<dd>Specifies whether this materialized query table can be used for query
optimization.
<dl class="parml">
<dt class="bold">ENABLE QUERY OPTIMIZATION</dt>
<dd>The materialized query table can be used for query optimization.
</dd>
<dt class="bold">DISABLE QUERY OPTIMIZATION</dt>
<dd>The materialized query table will not be used for query optimization.
The table can still be queried directly.
</dd>
</dl>
</dd>
</dl>
</dd>
<dt class="bold">SET <var class="pv">refreshable-table-alteration</var></dt>
<dd>Changes how the table is maintained or whether the table can be used
in query optimization.
<dl class="parml">
<dt class="bold">MAINTAINED BY USER</dt>
<dd>Specifies that the materialized query table is maintained by the user.
The user can use INSERT, DELETE, UPDATE, or REFRESH TABLE statements on the
table.
</dd>
<dt class="bold">REFRESH DEFERRED</dt>
<dd>Specifies that the data in the table can be refreshed at any time using
the REFRESH TABLE statement. The data in the table only reflects the result
of the query as a snapshot at the time when the REFRESH TABLE statement is
processed or when it was last updated.
</dd>
<dt class="bold">ENABLE QUERY OPTIMIZATION <span class="base">or</span> DISABLE
QUERY OPTIMIZATION</dt>
<dd>Specifies whether this materialized query table can be used for query
optimization.
<dl class="parml">
<dt class="bold">ENABLE QUERY OPTIMIZATION</dt>
<dd>The materialized query table can be used for query optimization.
</dd>
<dt class="bold">DISABLE QUERY OPTIMIZATION</dt>
<dd>The materialized query table will not be used for query optimization.
The table can still be queried directly.
</dd>
</dl>
</dd>
</dl>
</dd>
</dl>
<a name="wq1106"></a>
<h3 id="wq1106"><a href="rbafzmst02.htm#ToC_781">DROP MATERIALIZED QUERY</a></h3><a id="idx1479" name="idx1479"></a>
<p>Changes a materialized query table into a base table. If the specified
table is already a base table, an error is returned. The definition of columns
and data of the table are not changed, but the table can no longer be used
for query optimization and is no longer valid for use with the REFRESH TABLE
statement.</p>
<a name="wq1107"></a>
<h3 id="wq1107"><a href="rbafzmst02.htm#ToC_782">ACTIVATE NOT LOGGED INITIALLY</a></h3><a id="idx1480" name="idx1480"></a><a id="idx1481" name="idx1481"></a>
<p>Activates the NOT LOGGED INITIALLY attribute of the table for this current
unit of work.</p>
<p>Any changes made to the table by INSERT, DELETE, or UPDATE statements in
the same unit of work after the table is altered by this statement are not
logged (journaled).</p>
<p>At the completion of the current unit of work, the NOT LOGGED INITIALLY
attribute is deactivated and all operations that are done on the table in
subsequent units of work are logged (journaled).</p>
<p>ACTIVATE NOT LOGGED INITIALLY is not allowed in a transaction if data change
operations are pending for <var class="pv">table-name</var> or cursors are currently open
under commit that reference <var class="pv">table-name</var>.</p>
<p>ACTIVATE NOT LOGGED INITIALLY is ignored if the table has a
DATALINK column with FILE LINK CONTROL or if running with isolation level
No Commit (NC).</p>
<p></p>
<dl class="parml">
<dt class="bold">WITH EMPTY TABLE</dt><a id="idx1482" name="idx1482"></a>
<dd>Causes all data currently in the table to be removed. If
the unit of work in which this ALTER statement was issued is rolled back,
the table data will NOT be returned to its original state. When this action
is requested, no DELETE triggers defined on the affected table are fired.
<p>WITH EMPTY TABLE cannot be specified for a materialized query table
or for a parent in a referential constraint.</p>
<p>A DELETE statement without
a WHERE clause will typically perform as well or better than ACTIVATE NOT
LOGGED INITIALLY WITH EMPTY TABLE and will allow a ROLLBACK to rollback the
delete of the rows in the table.</p>
</dd>
</dl>
<a name="wq1108"></a>
<h3 id="wq1108"><a href="rbafzmst02.htm#ToC_783">VOLATILE or NOT VOLATILE</a></h3>
<p>Indicates to the optimizer whether or not the cardinality of table <var class="pv">table-name</var> can vary significantly at run time. Volatility applies to
the number of rows in the table, not to the table itself. The default is NOT
VOLATILE.</p>
<dl class="parml">
<dt class="bold">VOLATILE</dt><a id="idx1483" name="idx1483"></a>
<dd>Specifies that the cardinality of <var class="pv">table-name</var> can vary significantly
at run time, from empty to large. To access the table, the optimizer will
typically use an index, if possible.
</dd>
<dt class="bold">NOT VOLATILE</dt><a id="idx1484" name="idx1484"></a>
<dd>Specifies that the cardinality of <var class="pv">table-name</var> is not volatile.
Access plans that reference this table will be based on the cardinality of
the table at the time the access plan is built. NOT VOLATILE is the default.
</dd>
</dl>
<a name="wq1109"></a>
<h3 id="wq1109"><a href="rbafzmst02.htm#ToC_784">Notes</a></h3>
<p><span class="bold">Column references:</span> A column can only be referenced <span class="italic">once</span> in an ADD, ALTER, or DROP COLUMN clause in a single
ALTER TABLE statement. However, that same column can be referenced multiple
times for adding or dropping constraints in the same ALTER TABLE statement.</p>
<p><span class="bold">Order of operations:</span> The order of operations within
an ALTER TABLE statement is: </p>
<ul>
<li>drop constraints</li>
<li>drop materialized query table</li>
<li>drop partition</li>
<li>drop partitioning</li>
<li>drop columns for which the RESTRICT option was specified</li>
<li>alter all other column definitions
<ul>
<li>drop columns for which the CASCADE option was specified</li>
<li>alter column drop attributes (for example, DROP DEFAULT)</li>
<li>alter column alter attributes</li>
<li>alter column add attributes</li>
<li>add columns</li></ul></li>
<li>alter partition</li>
<li>add or alter materialized query table</li>
<li>add partition or add partitioning</li>
<li>add constraints</li></ul>
<p>Within each of these stages, the order in which the user specifies the
clauses is the order in which they are performed, with one exception. If
any columns are being dropped, that operation is logically done before any
column definitions are added or altered.</p>
<p><span class="bold">QTEMP considerations:</span> Any views or logical files
in another job's QTEMP that are dependent on the table being altered will
be dropped as a result of an ALTER TABLE statement.</p>
<p><span class="bold">Authority checking:</span> Authority checking is performed
only on the table being altered and any object explicitly referenced in the
ALTER TABLE statement (such as tables referenced in the fullselect). Other
objects may be accessed by the ALTER TABLE statement, but no authority to
those objects is required. For example, no authority is required on views
that exist on the table being altered, nor on dependent tables that reference
the table being altered through a referential constraint.</p>
<p><span class="bold">Backup recommendation:</span> It is strongly recommended
that a current backup of the table and dependent views and logical files exist
prior to altering a table.</p>
<p><span class="bold">Performance considerations:</span> The following performance
considerations apply to an ALTER TABLE statement when adding, altering, or
dropping columns from a table: </p>
<ul>
<li>The data in the table may be copied.<sup class="fn"><a id="wq1110" name="wq1110" href="rbafzmstatabl.htm#wq1111">56</a></sup>
<p>Adding
and dropping columns require the data to be copied.</p>
<p>Altering a column
usually requires the data to be copied. The data does not need to be copied,
however, if the alter only includes the following changes:</p>
<ul>
<li>The length attribute of a VARCHAR column is increasing and the current
length attribute is greater than 20.</li>
<li>The length attribute of a VARGRAPHIC column is increasing and the current
length attribute is greater than 10.</li>
<li>The allocated length of a VARCHAR column is changing and the current and
new allocated lengths are both less than or equal to 20.</li>
<li>The allocated length of a VARGRAPHIC column is changing and the current
and new allocated lengths are both less than or equal to 10.</li>
<li>The CCSID of a column is changing but no conversion is necessary between
the old and new CCSID. For example, if one CCSID is 65535, no data conversion
is necessary.</li>
<li>The default value is changing, and the length of the default value is
not greater than the current allocated length.</li>
<li>DROP DEFAULT is specified.</li>
<li>DROP NOT NULL is specified, but at least one nullable column will still
exist in the table after the alter table is complete.</li></ul></li>
<li>Indexes may need to be rebuilt.<sup class="fn"><a id="wq1112" name="wq1112" href="rbafzmstatabl.htm#wq1113">57</a></sup>
<p>An index does not
need to be rebuilt when columns are added to a table or when columns are dropped
or altered and those columns are not referenced in the index key.</p>
<p>Altering
a column that is used in the key of an index or constraint usually requires
the index to be rebuilt. The index does not need to be rebuilt, however, in
the following cases:</p>
<p></p>
<ul>
<li>The length attribute of a VARCHAR or VARGRAPHIC key is increasing.</li>
<li>The CCSID of a column is changing but no conversion is necessary between
the old and new CCSID. For example, if one CCSID is 65535.</li></ul></li></ul>
<p><span class="bold">Altering materialized query tables:</span> The isolation
level at the time when a base table is first altered to become a materialized
query table by the ALTER TABLE statement is the isolation level for the materialized
query table.</p>
<p>Altering a table to change it to a materialized query table with query
optimization enabled makes the table eligible for use in optimization. Therefore,
ensure that the data in the table is accurate. The DATA INITIALLY IMMEDIATE
clause can be used to refresh the data when the table is altered.</p>
<p><span class="bold">Syntax alternatives:</span> The following syntax is supported
for compatibility to prior releases. The syntax is non-standard and should
not be used:</p>
<ul>
<li>If an ADD constraint is the first clause of the ALTER TABLE
statement, the ADD keyword is optional, but strongly recommended. Otherwise,
it is required.</li>
<li><var class="pv">constraint-name</var> (without the CONSTRAINT keyword) may be specified
following the FOREIGN KEY keywords in a <var class="pv">referential-constraint</var>.</li>
<li>PART is a synonym for PARTITION.</li>
<li>PARTITION <var class="pv">partition-number</var> may be specified instead of PARTITION <var class="pv">partition-name</var>. A <var class="pv">partition-number</var> must not identify an existing
partition of the table or a partition that was previously specified in the
ALTER TABLE statement.
<p>If a <var class="pv">partition-number</var> is not specified,
a unique partition number is generated by the database manager.</p></li>
<li>VALUES is a synonym for ENDING AT.</li>
<li>SET MATERIALIZED QUERY AS DEFINITION ONLY is a synonym for DROP MATERIALIZED
QUERY.</li>
<li>SET SUMMARY AS DEFINITION ONLY is a synonym for DROP MATERIALIZED QUERY</li>
<li>SET MATERIALIZED QUERY AS (<var class="pv">select-statement</var>) is a synonym for
ADD MATERIALIZED QUERY (<var class="pv">select-statement</var>)</li>
<li>SET SUMMARY AS (<var class="pv">select-statement</var>) is a synonym for ADD MATERIALIZED
QUERY (<var class="pv">select-statement</var>)</li></ul>
<a name="wq1114"></a>
<h3 id="wq1114"><a href="rbafzmst02.htm#ToC_785">Cascaded Effects</a></h3>
<p>Adding a column has no cascaded effects to SQL views or most logical
files.<sup class="fn"><a href="rbafzmstatabl.htm#fn23">58</a></sup> For example, adding a column to a table does not
cause the column to be added to any dependent views, even if those views were
created with a SELECT * clause.</p>
<p>Dropping or altering a column may cause several cascaded effects. <a href="rbafzmstatabl.htm#dropcas">Table 46</a> lists the cascaded effects of dropping a column.</p>
<a name="dropcas"></a>
<table id="dropcas" width="100%" summary="" border="1" frame="border" rules="all">
<caption>Table 46. Cascaded effects of dropping a column</caption>
<thead valign="bottom">
<tr>
<th id="wq1115" width="20%" align="left" valign="bottom">Operation</th>
<th id="wq1116" width="39%" align="left" valign="bottom">RESTRICT Effect</th>
<th id="wq1117" width="40%" align="left" valign="bottom">CASCADE Effect</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced by a view</td>
<td align="left" valign="top" headers="wq1116">The drop of the column is not allowed.</td>
<td align="left" valign="top" headers="wq1117">The view and all views dependent on that
view are dropped.</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced by a non-view
logical file</td>
<td align="left" valign="top" headers="wq1116">The drop is allowed, and the column is dropped
from the logical file if:
<ul>
<li>The logical file shares a format with the file being altered, and</li>
<li>The dropped column is not used as a key field or in select/omit specifications,
and</li>
<li>That format is not used again in the logical file with another based-on
file.</li></ul>Otherwise, the drop of the column is not allowed.</td>
<td align="left" valign="top" headers="wq1117">The drop is allowed, and the column is dropped
from the logical file if:
<ul>
<li>The logical file shares a format with the file being altered, and</li>
<li>The dropped column is not used as a key field or in select or omit specifications,
and</li>
<li>That format is not used again in the logical file with another based-on
file.</li></ul>Otherwise, the logical file is dropped.</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced in the key of
an index</td>
<td align="left" valign="top" headers="wq1116">The drop of the index is not allowed.</td>
<td align="left" valign="top" headers="wq1117">The index is dropped.</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced in a unique constraint</td>
<td align="left" valign="top" headers="wq1116">If all the columns referenced in the unique
constraint are dropped in the same ALTER COLUMN statement and the unique constraint
is not referenced by a referential constraint, the columns and the constraint
are dropped. (Hence, the index used to satisfy the constraint is also dropped.)
For example, if column A is dropped, and a unique constraint of UNIQUE (A)
or PRIMARY KEY (A) exists and no referential constraints reference the unique
constraint, the operation is allowed.
<p>Otherwise, the drop of the column
is not allowed.</p></td>
<td align="left" valign="top" headers="wq1117">The unique constraint is dropped as are any
referential constraints that refer to that unique constraint. (Hence, any
indexes used by those constraints are also dropped).</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced in a referential
constraint</td>
<td align="left" valign="top" headers="wq1116">If all the columns referenced in the referential
constraint are dropped at the same time, the columns and the constraint are
dropped. (Hence, the index used by the foreign key is also dropped). For example,
if column B is dropped and a referential constraint of FOREIGN KEY (A) exists,
the operation is allowed.
<p>Otherwise, the drop of the column is not allowed.</p></td>
<td align="left" valign="top" headers="wq1117">The referential constraint is dropped. (Hence,
the index used by the foreign key is also dropped).</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced in a trigger</td>
<td align="left" valign="top" headers="wq1116">The drop of the column is not allowed.</td>
<td align="left" valign="top" headers="wq1117">The trigger is dropped.</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1115">Drop of a column referenced in an MQT</td>
<td align="left" valign="top" headers="wq1116">The drop of the column is not allowed.</td>
<td align="left" valign="top" headers="wq1117">The MQT is dropped.</td>
</tr>
</tbody>
</table>
<p><a href="rbafzmstatabl.htm#alterca">Table 47</a> lists the cascaded effects of altering a column.
(Alter of a column in the following chart means altering a data type, precision,
scale, length, or nullability characteristic.)</p>
<a name="alterca"></a>
<table id="alterca" width="100%" summary="" border="1" frame="border" rules="all">
<caption>Table 47. Cascaded effects of altering a column</caption>
<thead valign="bottom">
<tr>
<th id="wq1118" width="20%" align="left" valign="bottom">Operation</th>
<th id="wq1119" width="80%" align="left" valign="bottom">Effect</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced by a view</td>
<td align="left" valign="top" headers="wq1119">The alter is allowed.
<p>The views that are
dependent on the table will be recreated. The new column attributes will be
used when recreating the views.</p></td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced by a non-view
logical file</td>
<td align="left" valign="top" headers="wq1119">The alter is allowed.
<p>The non-view logical
files that are dependent on the table will be recreated. If the logical file
shares a format with the file being altered, and that format is not used again
in the logical file with another based-on file, the new column attributes
will be used when recreating the logical file.</p>
<p>Otherwise, the new column
attributes will not be used when recreating the logical file. Instead, the
current logical file attributes are used.</p></td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced in the key of
an index.</td>
<td align="left" valign="top" headers="wq1119">The alter is allowed. (Hence, the index will
usually be rebuilt.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced in a unique
constraint</td>
<td align="left" valign="top" headers="wq1119">The alter is allowed. (Hence, the index will
usually be rebuilt.)
<p>If the unique constraint is referenced by a referential
constraint, the attributes of the foreign keys no longer match the attributes
of the unique constraint. The constraint will be placed in a defined and check-pending
state.</p></td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced in a referential
constraint</td>
<td align="left" valign="top" headers="wq1119">The alter is allowed.
<ul>
<li>If the referential constraint is in the defined but check-pending state,
the alter is allowed and an attempt is made to put the constraint in the enabled
state. (Hence, the index used to satisfy the unique constraint will usually
to be rebuilt.)</li>
<li>If the referential constraint is in the enabled state, the constraint
is placed in the defined and check-pending state.</li></ul></td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced in a trigger</td>
<td align="left" valign="top" headers="wq1119">The trigger is preserved.</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq1118">Alter of a column referenced in an MQT</td>
<td align="left" valign="top" headers="wq1119">The MQT is recreated to include the new attributes.</td>
</tr>
</tbody>
</table>
<a name="wq1120"></a>
<h3 id="wq1120"><a href="rbafzmst02.htm#ToC_786">Examples</a></h3>
<p><span class="italic">Example 1:</span> Add a new column named RATING, which
is one character long, to the DEPARTMENT table. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> DEPARTMENT
<span class="bold">ADD</span> RATING <span class="bold">CHAR</span></pre>
<p><span class="italic">Example 2:</span> Add a new column named PICTURE_THUMBNAIL
to the EMPLOYEE table. Create PICTURE_THUMBNAIL as a BLOB column with
a maximum length of 1K characters.</p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EMPLOYEE
<span class="bold">ADD</span> PICTURE_THUMBNAIL <span class="bold"> BLOB(</span>1K<span class="bold">)</span></pre>
<p><span class="italic">Example 3:</span> Assume a new table EQUIPMENT has been
created with the following columns: </p>
<dl>
<dt class="bold">&nbsp;&nbsp;EQUIP_NO </dt>
<dd>INT
</dd>
<dt class="bold">&nbsp;&nbsp;EQUIP_DESC </dt>
<dd>VARCHAR(50)
</dd>
<dt class="bold">&nbsp;&nbsp;LOCATION </dt>
<dd>VARCHAR(50)
</dd>
<dt class="bold">&nbsp;&nbsp;EQUIP_OWNER </dt>
<dd>CHAR(3)
</dd>
</dl><p class="indatacontent"> Add a referential constraint to the EQUIPMENT table so that the owner
(EQUIP_OWNER) must be a department number (DEPTNO) that is present in the
DEPARTMENT table. If a department is removed from the DEPARTMENT table, the
owner (EQUIP_OWNER) values for all equipment owned by that department should
become unassigned (or set to null). Give the constraint the name DEPTQUIP. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EQUIPMENT
<span class="bold">FOREIGN KEY</span> DEPTQUIP <span class="bold">(</span>EQUIP_OWNER<span class="bold">)
REFERENCES</span> DEPARTMENT
<span class="bold"> ON DELETE SET NULL</span></pre><p class="indatacontent">Change the default value
for the EQUIP_OWNER column to 'ABC'. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EQUIPMENT
<span class="bold">ALTER COLUMN</span> EQUIP_OWNER
<span class="bold">SET DEFAULT</span> 'ABC'</pre><p class="indatacontent">Drop the LOCATION column.
Also drop any views, indexes, or constraints that are built on that column. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EQUIPMENT
<span class="bold">DROP COLUMN</span> LOCATION <span class="bold">CASCADE</span></pre><p class="indatacontent">Alter
the table so that a new column called SUPPLIER is added, the existing column
called LOCATION is dropped, a unique constraint over the new column SUPPLIER
is added, and a primary key is built over the existing column EQUIP_NO. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EQUIPMENT
<span class="bold">ADD COLUMN</span> SUPPLIER INT
<span class="bold">DROP COLUMN</span> LOCATION
<span class="bold">ADD UNIQUE</span> SUPPLIER
<span class="bold">ADD PRIMARY KEY</span> EQUIP_NO</pre><p class="indatacontent">Notice that the column
EQUIP_DESC is a variable length column. If an allocated length of 25 was specified,
the following ALTER TABLE statement would not change that allocated length. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EQUIPMENT
<span class="bold">ALTER COLUMN</span> EQUIP_DESC
<span class="bold">SET DATA TYPE</span> VARCHAR(60)</pre>
<p><span class="italic">Example 4:</span> Alter the EMPLOYEE table. Add the check
constraint named REVENUE defined so that each employee must make a total of
salary and commission greater than $30,000. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EMPLOYEE
<span class="bold">ADD CONSTRAINT</span> REVENUE
<span class="bold">CHECK</span> (SALARY + COMM > 30000)</pre>
<p><span class="italic">Example 5:</span> Alter EMPLOYEE table. Drop the constraint
REVENUE which was previously defined. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EMPLOYEE
<span class="bold">DROP CONSTRAINT</span> REVENUE </pre>
<p><span class="italic">Example 6:</span> Alter the EMPLOYEE table. Alter the
column PHONENO to accept up to 20 characters for a phone number. </p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> EMPLOYEE
<span class="bold">ALTER COLUMN</span> PHONENO <span class="bold">SET DATA TYPE VARCHAR (20)</span></pre>
<p><span class="italic">Example 7:</span> Alter the base table TRANSCOUNT to
a materialized query table. The result of the <var class="pv">select-statement</var> must
provide a set of columns that match the columns in the existing table (same
number of columns and compatible attributes).</p>
<pre class="xmp"> <span class="bold">ALTER TABLE</span> TRANSCOUNT
<span class="bold">ADD MATERIALIZED QUERY</span>
<span class="bold">(SELECT</span> ACCTID, LOCID, YEAR, <span class="bold">COUNT(*) AS</span> CNT
<span class="bold">FROM</span> TRANS
<span class="bold">GROUP BY</span> ACCTID, LOCID, YEAR <span class="bold">)</span>
<span class="bold">DATA INITIALLY DEFERRED</span>
<span class="bold">REFRESH DEFERRED</span>
<span class="bold">MAINTAINED BY USER</span> </pre><a id="idx1485" name="idx1485"></a><a id="idx1486" name="idx1486"></a>
<hr /><div class="fnnum"><a id="trgdep" name="trgdep">55</a>.</div>
<div class="fntext">A trigger is dependent on the column if it is referenced in the
UPDATE OF column list or anywhere in the triggered action.</div><div class="fnnum"><a id="wq1111" name="wq1111" href="rbafzmstatabl.htm#wq1110">56</a>.</div>
<div class="fntext">In cases where enough storage
does not exist to make a complete copy, a special copy that only requires
approximately 16-32 megabytes of free storage is performed.</div><div class="fnnum"><a id="wq1113" name="wq1113" href="rbafzmstatabl.htm#wq1112">57</a>.</div>
<div class="fntext">Any indexes that need to be rebuilt
are rebuilt asynchronously by database server jobs.</div><div class="fnnum"><a id="fn23" name="fn23">58</a>.</div>
<div class="fntext">A column will also be added to a logical file that shares
its physical file's format when a column is added to that physical file (unless
that format is used again in the logical file with another based-on file).</div>
<br />
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