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<?xml version="1.0" encoding="utf-8"?>
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<meta name="keywords" content="data types, SQL (Structured Query Language),
description, data type, null value, defined, null value in SQL, numbers, numeric,
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<title>Data types</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="ch2data"></a>
<h2 id="ch2data"><a href="rbafzmst02.htm#ToC_97">Data types</a></h2><a id="idx304" name="idx304"></a><a id="idx305" name="idx305"></a>
<p>The smallest unit of data that can be manipulated in SQL is called a <span class="italic">value.</span> How values are interpreted depends on the data
type of their source. The sources of values are: </p>
<ul>
<li>Columns</li>
<li>Constants</li>
<li>Expressions</li>
<li>Functions</li>
<li>Special registers</li>
<li>Variables (such as host variables, SQL variables, parameter markers and
parameters of routines)</li></ul>
<p>The DB2&reg; UDB relational database products support both built-in data types
and user-defined data types. This section describes the built-in data types.
For a description of distinct types, see <a href="rbafzmstch2data.htm#ch2udf">User-defined types</a>.</p>
<p> The following figure illustrates the various built-in data types supported
by the DB2 UDB for iSeries program.</p>
<a name="wq75"></a>
<div class="fignone" id="wq75">
<div class="mmobj">
<img src="rbafz501.gif" alt="Supported data types: Datalink, Time, Timestamp, Date, Char, Varchar, Clob, Graphic, Vargraphic, Dbclob, Binary, Varbinary, Blob, Real, Double, Rowid, Smallint, Integer, Bigint, Decimal, and Numeric." /></div></div>
<p>For more details on data types, see the following topics:</p>
<ul>
<li><a href="rbafzmstch2data.htm#ch2num">Numbers</a></li>
<li><a href="rbafzmstch2data.htm#charstrg">Character strings</a></li>
<li><a href="rbafzmstch2data.htm#charsubtype">Character encoding schemes</a></li>
<li><a href="rbafzmstch2data.htm#graphicstrg">Graphic strings</a></li>
<li><a href="rbafzmstch2data.htm#graphicsubtype">Graphic encoding schemes</a></li>
<li><a href="rbafzmstch2data.htm#binarystrg">Binary strings</a></li>
<li><a href="rbafzmstch2data.htm#lobs">Large objects</a></li>
<li><a href="rbafzmstch2data.htm#ch2datetime">Datetime values</a></li>
<li><a href="rbafzmstch2data.htm#ch2datalink">DataLink values</a></li>
<li><a href="rbafzmstch2data.htm#ch2rowid">Row ID values</a></li>
<li><a href="rbafzmstch2data.htm#ch2udf">User-defined types</a></li></ul>
<p>For information about specifying the data types of columns, see <a href="rbafzmsthctabl.htm#hctabl">CREATE TABLE</a>.</p>
<a name="wq76"></a>
<h3 id="wq76"><a href="rbafzmst02.htm#ToC_98">Nulls</a></h3>
<p><a id="idx306" name="idx306"></a><a id="idx307" name="idx307"></a></p>
<p>All data types include the null value. Distinct from all non-null
values, the null value is a special value that denotes the absence of a (non-null)
value. Except for grouping operations, a null value is also distinct from
another null value. Although all data types include the null value, some sources
of values cannot provide the null value. For example, constants, columns that
are defined as NOT NULL, and special registers cannot contain null values;
the COUNT and COUNT_BIG functions cannot return a null value; and ROWID columns
cannot store a null value although a null value can be returned for a ROWID
column as the result of a query.</p>
<a name="ch2num"></a>
<h3 id="ch2num"><a href="rbafzmst02.htm#ToC_99">Numbers</a></h3><a id="idx308" name="idx308"></a><a id="idx309" name="idx309"></a><a id="idx310" name="idx310"></a><a id="idx311" name="idx311"></a><a id="idx312" name="idx312"></a>
<p>The numeric data types are binary integer, floating-point, and decimal.
Binary integer includes small integer, large integer, and big integer. Floating-point
includes single precision and double precision. Binary numbers are exact representations
of integers. Decimal numbers are exact representations of real numbers. Binary
and decimal numbers are considered exact numeric types. Floating-point numbers
are approximations of real numbers and are considered approximate numeric
types.</p>
<p>All numbers have a <span class="italic">sign,</span> a <span class="italic">precision,</span> and a <span class="italic">scale</span>. <a id="idx313" name="idx313"></a>If a column value is zero,
the sign is positive. The precision is the total number of binary or decimal
digits excluding the sign. The scale is the total number of binary or decimal
digits to the right of the decimal point. If there is no decimal point, the
scale is zero.</p>
<a name="wq77"></a>
<h4 id="wq77">Small integer</h4><a id="idx314" name="idx314"></a><a id="idx315" name="idx315"></a><a id="idx316" name="idx316"></a><a id="idx317" name="idx317"></a>
<p>A <span class="italic">small integer</span> is a binary number composed of
2 bytes with a precision of 5 digits. The range of small integers is -32768
to +32767.</p>
<p>For small integers, decimal precision and scale are supported by COBOL, RPG,
and iSeries system files. For information concerning the precision and scale
of binary integers, see the <a href="../rzahg/rzahgdds.htm">DDS Reference</a> book.</p>
<a name="wq78"></a>
<h4 id="wq78">Large integer</h4><a id="idx318" name="idx318"></a><a id="idx319" name="idx319"></a>
<p>A <span class="italic">large integer</span> is a binary number composed of
4 bytes with a precision of 10 digits. The range of large integers is -2147483648
to +2147483647.</p>
<p>For large integers, decimal precision and scale are supported by COBOL, RPG,
and iSeries system files. For information concerning the precision and scale
of binary integers, see the <a href="../rzahg/rzahgdds.htm">DDS Reference</a> book.</p>
<a name="wq79"></a>
<h4 id="wq79">Big integer</h4><a id="idx320" name="idx320"></a><a id="idx321" name="idx321"></a>
<p>A <span class="italic">big integer</span> is a binary number composed of 8
bytes with a precision of 19 digits. The range of big integers is -9223372036854775808
to +9223372036854775807.</p>
<a name="wq80"></a>
<h4 id="wq80">Floating-point</h4><a id="idx322" name="idx322"></a><a id="idx323" name="idx323"></a>
<p>A <span class="italic">single-precision floating-point</span> number is a 32-bit
approximate representation of a real number. The range of magnitude is approximately
1.17549436 &times; 10<sup>-38</sup> to 3.40282356
&times; 10<sup>38</sup>.</p><a id="idx324" name="idx324"></a>
<p>A <span class="italic">double-precision floating-point</span> number is a IEEE 64-bit
approximate representation of a real number. The range of magnitude is approximately
2.2250738585072014 &times; 10<sup>-308</sup> to 1.7976931348623158
&times; 10<sup>308</sup>.</p>
<p>See <a href="rbafzmstlimtabs.htm#btable1">Table 77</a> for more information.</p>
<a name="wq81"></a>
<h4 id="wq81">Decimal</h4><a id="idx325" name="idx325"></a><a id="idx326" name="idx326"></a><a id="idx327" name="idx327"></a>
<p>A <span class="italic">decimal</span> value is a packed decimal or zoned decimal
number with an implicit decimal point. The position of the decimal point is
determined by the precision and the scale of the number. The scale, which
is the number of digits in the fractional part of the number, cannot be negative
or greater than the precision. The maximum precision is 63 digits.</p>
<p>All values of a decimal column have the same precision and scale. The range
of a decimal variable or the numbers in a decimal column is <span class="italic">-n</span> to +<span class="italic">n</span>, where the absolute value of <span class="italic">n</span> is the largest number that can be represented with the applicable precision
and scale.</p>
<p>The maximum range is negative 10<sup>63</sup>+1 to 10<sup>63</sup> minus 1.</p>
<a name="wq82"></a>
<h4 id="wq82">Numeric variables</h4>
<p>Small and large binary integer variables can be used in all host languages.
Big integer variables can only be used in C, C++, ILE COBOL, and ILE RPG.
Floating-point variables can be used in all host languages except RPG/400&reg; and COBOL/400&reg;. Decimal variables can be used in all supported host languages.</p>
<a name="numstrng"></a>
<h4 id="numstrng">String representations of numeric values</h4><a id="idx328" name="idx328"></a><a id="idx329" name="idx329"></a><a id="idx330" name="idx330"></a><a id="idx331" name="idx331"></a>
<p>When a decimal or floating-point number is cast to a string (for example,
using a CAST specification) the implicit decimal point is replaced by the
default decimal separator character in effect when the statement was prepared.
When a string is cast to a decimal or floating-point value (for example, using
a CAST specification), the default decimal separator character in effect when
the statement was prepared is used to interpret the string.</p>
<a name="charstrg"></a>
<h3 id="charstrg"><a href="rbafzmst02.htm#ToC_107">Character strings</a></h3><a id="idx332" name="idx332"></a><a id="idx333" name="idx333"></a><a id="idx334" name="idx334"></a><a id="idx335" name="idx335"></a><a id="idx336" name="idx336"></a><a id="idx337" name="idx337"></a>
<p>A <span class="italic">character string</span> is a sequence of bytes. The
length of the string is the number of bytes in the sequence. If the length
is zero, the value is called the <span class="italic">empty string</span>. The
empty string should not be confused with the null value.</p>
<a name="wq83"></a>
<h4 id="wq83">Fixed-length character strings</h4><a id="idx338" name="idx338"></a>
<p>All values of a fixed-length character-string column have the same length.
This is determined by the length attribute of the column. The length attribute
must be between 1 through 32766 inclusive.</p>
<a name="wq84"></a>
<h4 id="wq84">Varying-length character strings</h4>
<p>The types of varying-length character strings are:</p>
<ul>
<li>VARCHAR (or synonyms CHAR VARYING and CHARACTER VARYING)</li>
<li>CLOB (or synonyms CHAR LARGE OBJECT and CHARACTER LARGE OBJECT)</li></ul>
<p>The values of a column with any one of these string types can have different
lengths. The length attribute of the column determines the maximum length
a value can have.</p>
<p>For a VARCHAR column, the length attribute must be between 1 through 32740
inclusive. For a CLOB column, the length attribute must be between 1 through
2&nbsp;147&nbsp;483&nbsp;647 inclusive. For more information about CLOBs, see <a href="rbafzmstch2data.htm#lobs">Large objects</a>.</p>
<p>For the restrictions that apply to the use of long varying-length strings,
see <a href="rbafzmstch2data.htm#limstr">Limitations on use of strings</a>.</p>
<a name="wq85"></a>
<h4 id="wq85">Character-string variables</h4><a id="idx339" name="idx339"></a><a id="idx340" name="idx340"></a><a id="idx341" name="idx341"></a><a id="idx342" name="idx342"></a><a id="idx343" name="idx343"></a><a id="idx344" name="idx344"></a><a id="idx345" name="idx345"></a>
<ul>
<li>Fixed-length character-string variables can be used in all host languages
except REXX. (In C, fixed-length character-string variables are limited to
a length of 1.)</li>
<li>VARCHAR varying-length character-string variables can be used in C, COBOL,
PL/I, REXX, and RPG:
<ul>
<li>In PL/I, REXX, and ILE RPG, there is a varying-length character-string
data type.</li>
<li>In COBOL and C, varying-length character strings are represented as structures.</li>
<li>In C, varying-length character-string variables can also be represented
by NUL-terminated strings.</li>
<li>In RPG/400, varying-length character-string variables can only be represented
by VARCHAR columns included as a result of an externally described data structure.</li></ul></li>
<li>CLOB varying-length character-string variables can be defined in all
host languages except REXX, RPG/400, and COBOL/400.
<ul>
<li>In ILE RPG, a CLOB varying-length character string is declared using the
SQLTYPE keyword.</li>
<li>In all other languages, an SQL TYPE IS CLOB clause is used.</li></ul></li></ul>
<a name="charsubtype"></a>
<h3 id="charsubtype"><a href="rbafzmst02.htm#ToC_111">Character encoding schemes</a></h3>
<p>Each character string is further defined as one of: </p>
<dl><a id="idx346" name="idx346"></a><a id="idx347" name="idx347"></a>
<dt class="bold">Bit data</dt>
<dd>Data that is not associated with a coded character set and is therefore
never converted. The CCSID for bit data is 65535.
</dd>
<dt class="bold">SBCS data</dt><a id="idx348" name="idx348"></a><a id="idx349" name="idx349"></a>
<dd>Data in which every character is represented by a single byte. Each
SBCS data character string has an associated CCSID. If necessary, an SBCS
string is converted before it is used in an operation with a character string
that has a different CCSID.
</dd>
<dt class="bold">Mixed data</dt><a id="idx350" name="idx350"></a><a id="idx351" name="idx351"></a>
<dd>Data that may contain a mixture of characters from a single-byte character
set (SBCS) and a double-byte character set (DBCS). Each mixed string has
an associated CCSID. If necessary, a mixed data character string is converted
before an operation with a character string that has a different CCSID. If
mixed data contains a DBCS character, it cannot be converted to SBCS data.
</dd>
<dt class="bold">Unicode data</dt><a id="idx352" name="idx352"></a>
<dd>Data that contains characters represented by one or more bytes. Each
Unicode character string is encoded using UTF-8. The CCSID for UTF-8 is 1208.
</dd>
</dl>
<p>The database manager does not recognize subclasses of double-byte characters,
and it does not assign any specific meaning to particular double-byte codes.
However, if you choose to use mixed data, then two single-byte EBCDIC codes
are given special meanings: </p>
<ul>
<li><span class="hex">X'0E'</span>, the &quot;shift-out&quot; character, is used to mark the
beginning of a sequence of double-byte codes.</li>
<li><span class="hex">X'0F'</span>, the &quot;shift-in&quot; character, is used to mark the end
of a sequence of double-byte codes.</li></ul>
<p>In order for the database manager to recognize double-byte characters in
a mixed data character string, the following condition must be met: </p>
<ul class="simple">
<li>Within the string, the double-byte characters must be enclosed between
paired shift-out and shift-in characters.
<p>The pairing is detected as the
string is read from left to right. The code <span class="hex">X'0E'</span> is recognized as
a shift out character if <span class="hex">X'0F'</span> occurs later; otherwise, it is invalid.
The first <span class="hex">X'0F'</span> following the <span class="hex">X'0E'</span> that is on a double-byte
boundary is the paired shift-in character. Any <span class="hex">X'0F'</span> that is not on
a double-byte boundary is not recognized.</p>
<p>There must be an even number
of bytes between the paired characters, and each pair of bytes is considered
to be a double-byte character. There can be more than one set of paired shift-out
and shift-in characters in the string.</p></li></ul>
<p>The length of a mixed data character string is its total number of bytes,
counting two bytes for each double-byte character and one byte for each shift-out
or shift-in character.</p>
<p>When the job CCSID indicates that DBCS is allowed, CREATE TABLE will create
character columns as DBCS-Open fields, unless FOR BIT DATA, FOR SBCS DATA,
or an SBCS CCSID is specified. The SQL user will see these as character fields,
but the system database support will see them as DBCS-Open fields. For a definition
of a DBCS-Open field, see the <a href="../dbp/rbafokickoff.htm">Database Programming</a> book.</p>
<a name="graphicstrg"></a>
<h3 id="graphicstrg"><a href="rbafzmst02.htm#ToC_112">Graphic strings</a></h3><a id="idx353" name="idx353"></a>
<p>A <var class="pv">graphic string</var> is a sequence of two-byte characters. The length
of the string is the number of its characters. Like character strings, graphic
strings can be empty.</p>
<a name="wq86"></a>
<h4 id="wq86">Fixed-length graphic strings</h4>
<p>All values of a fixed-length graphic-string column have the same length,
which is determined by the length attribute of the column. The length attribute
must be between 1 through 16383 inclusive.</p>
<a name="wq87"></a>
<h4 id="wq87">Varying-length graphic strings</h4>
<p>The types of varying-length graphic strings are:</p>
<ul>
<li>VARGRAPHIC (or synonym GRAPHIC VARYING)</li>
<li>DBCLOB</li></ul>
<p>The values of a column with any one of these string types can have different
lengths. The length attribute of the column determines the maximum length
a value can have.</p>
<p>For a VARGRAPHIC column, the length attribute must be between 1 through
16370 inclusive. For a DBCLOB column, the length attribute must be between
1 through 1 073 741 823 inclusive. For more information about DBCLOBs, see <a href="rbafzmstch2data.htm#lobs">Large objects</a>.</p>
<p>For the restrictions that apply to the use of long varying-length strings,
see <a href="rbafzmstch2data.htm#limstr">Limitations on use of strings</a>.</p>
<a name="wq88"></a>
<h4 id="wq88">Graphic-string variables</h4><a id="idx354" name="idx354"></a>
<ul>
<li>Fixed-length graphic-string variables can be defined in C, ILE COBOL,
and ILE RPG. (In C, fixed-length graphic-string variables are limited to a
length of 1.)
<p>Although fixed-length graphic-string variables cannot be
defined in PL/I, COBOL/400, and RPG/400, a character-string variable will
be treated like a fixed-length graphic-string variable if it was generated
in the source from a GRAPHIC column in the external definition of a file.</p></li>
<li>VARGRAPHIC varying-length graphic-string variables can be defined in C,
ILE COBOL, REXX, and ILE RPG.
<ul>
<li>In REXX and ILE RPG, there is a varying-length graphic-string data type.</li>
<li>In C and ILE COBOL, varying-length graphic strings are represented as
structures.</li>
<li>In C, varying-length graphic-string variables can also be represented
by NUL-terminated graphic strings.</li>
<li>Although varying-length graphic-string variables cannot be defined in
PL/I, COBOL/400, and RPG/400, a character-string variable will be treated like
a varying-length graphic-string variable if it was generated in the source
from a VARGRAPHIC column in the external definition of a file.</li></ul></li>
<li>DBCLOB varying-length character-string variables can be defined in all
host languages except REXX, RPG/400, and COBOL/400.
<ul>
<li>In ILE RPG, a DBCLOB varying-length character string is declared using
the SQLTYPE keyword.</li>
<li>In all other languages, an SQL TYPE IS DBCLOB clause is used.</li></ul></li></ul>
<a name="graphicsubtype"></a>
<h3 id="graphicsubtype"><a href="rbafzmst02.htm#ToC_116">Graphic encoding schemes</a></h3>
<p>Each graphic string is further defined as one of:</p>
<dl>
<dt class="bold">DBCS data</dt><a id="idx355" name="idx355"></a>
<dd>Data in which every character is represented by a character from the
double-byte character set (DBCS) that does not include the shift-out or shift-in
characters.
<p>Every DBCS graphic string has a CCSID that identifies a double-byte
coded character set. If necessary, a DBCS graphic string is converted before
it is used in an operation with a DBCS graphic string that has a different
DBCS CCSID.</p>
</dd>
<dt class="bold">Unicode data</dt>
<dd>Data that contains characters represented by two or more bytes. Each
Unicode graphic string is encoded using either UCS-2 or UTF-16. UCS-2 is a
subset of UTF-16.<a id="idx356" name="idx356"></a><a id="idx357" name="idx357"></a> The CCSID for
UCS-2 is 13488. The CCSID for UTF&ndash;16 is 1200.
</dd>
</dl>
<p>When graphic-string variables are not explicitly tagged with a CCSID, the
associated DBCS CCSID for the job CCSID is used. If no associated DBCS CCSID
exists, the variable is tagged with 65535. A graphic-string variable is never
implicitly tagged with a UTF-16 or UCS-2 CCSID. See the DECLARE VARIABLE statement
for information on how to tag a graphic variable with a CCSID.</p>
<a name="binarystrg"></a>
<h3 id="binarystrg"><a href="rbafzmst02.htm#ToC_117">Binary strings</a></h3><a id="idx358" name="idx358"></a><a id="idx359" name="idx359"></a><a id="idx360" name="idx360"></a><a id="idx361" name="idx361"></a><a id="idx362" name="idx362"></a><a id="idx363" name="idx363"></a>
<p>A <span class="italic">binary string</span> is a sequence of bytes. The length
of a binary string is the number of bytes in the sequence. A binary string
has a CCSID of 65535.</p>
<a name="wq89"></a>
<h4 id="wq89">Fixed-length binary strings</h4><a id="idx364" name="idx364"></a>
<p>All values of a fixed-length binary-string column have the same length.
This is determined by the length attribute of the column. The length attribute
must be between 1 through 32766 inclusive.</p>
<a name="wq90"></a>
<h4 id="wq90">Varying-length binary strings</h4>
<p>The types of varying-length binary strings are:</p>
<ul>
<li>VARBINARY (or synonym BINARY VARYING)</li>
<li>BLOB (or synonym BINARY LARGE OBJECT)</li></ul>
<p>The values of a column with any one of these string types can have different
lengths. The length attribute of the column determines the maximum length
a value can have.</p>
<p>For a VARBINARY column, the length attribute must be between 1 through
32740 inclusive. For a BLOB column, the length attribute must be between 1
through 2&nbsp;147&nbsp;483&nbsp;647 bytes inclusive. For more information about
BLOBs, see <a href="rbafzmstch2data.htm#lobs">Large objects</a>.</p>
<a name="wq91"></a>
<h4 id="wq91">Binary-string variables</h4>
<p>A variable with a binary string type can be defined in all host languages
except REXX, RPG/400, and COBOL/400.</p>
<ul>
<li>BINARY fixed-length binary-string variables can be defined in all host
languages except REXX, RPG/400, and COBOL/400.
<ul>
<li>In ILE RPG, a BINARY fixed-length binary-string variable is declared using
the SQLTYPE keyword.</li>
<li>In all other languages, an SQL TYPE IS BINARY clause is used.</li></ul></li>
<li>VARBINARY varying-length binary-string variables can be defined in all
host languages except REXX, RPG/400, and COBOL/400.
<ul>
<li>In ILE RPG, a VARBINARY varying-length binary-string variable is declared
using the SQLTYPE keyword.</li>
<li>In all other languages, an SQL TYPE IS VARBINARY clause is used.</li></ul></li>
<li>BLOB varying-length binary-string variables can be defined in all host
languages except REXX, RPG/400, and COBOL/400.
<ul>
<li>In ILE RPG, a BLOB varying-length binary-string variable is declared using
the SQLTYPE keyword.</li>
<li>In all other languages, an SQL TYPE IS BLOB clause is used.</li></ul></li></ul>
<p>Although binary strings and FOR BIT DATA character strings might be used
for similar purposes, the two data types are not compatible. The BINARY, BLOB,
and VARBINARY functions can be used to change a FOR BIT DATA character string
into a binary string.</p>
<a name="lobs"></a>
<h3 id="lobs"><a href="rbafzmst02.htm#ToC_121">Large objects</a></h3><a id="idx365" name="idx365"></a><a id="idx366" name="idx366"></a><a id="idx367" name="idx367"></a><a id="idx368" name="idx368"></a><a id="idx369" name="idx369"></a><a id="idx370" name="idx370"></a>
<p>The term <span class="italic">large object</span> and the generic acronym <span class="italic">LOB</span> are used to refer to any CLOB, DBCLOB, or BLOB data
type.</p>
<a name="mlobloc"></a>
<h4 id="mlobloc">Manipulating large objects with locators</h4><a id="idx371" name="idx371"></a><a id="idx372" name="idx372"></a><a id="idx373" name="idx373"></a>
<p>Since LOB values can be very large, the transfer of these values from the
database server to client application program variables can be time consuming.
Also, application programs typically process LOB values a piece at a time,
rather than as a whole. For these cases, the application can reference
a LOB value via a large object locator (LOB locator). <sup class="fn"><a id="wq92" name="wq92" href="rbafzmstch2data.htm#wq93">19</a></sup></p>
<p>A <span class="italic">large object locator</span> or LOB locator is a variable
with a value that represents a single LOB value in the database server. LOB
locators were developed to provide users with a mechanism by which they could
easily manipulate very large objects in application programs without requiring
them to store the entire LOB value on the client machine where the application
program may be running.</p>
<p>For example, when selecting a LOB value, an application program
could select the entire LOB value and place it into an equally large variable
(which is acceptable if the application program is going to process the entire
LOB value at once), or it could instead select the LOB value into a LOB locator.
Then, using the LOB locator, the application program can issue subsequent
database operations on the LOB value by supplying the locator value as input.
The resulting output of the locator operation, for example the amount of data
assigned to a client variable, would then typically be a small subset of the
input LOB value.</p>
<p>LOB locators may also represent more than just base values; they can also
represent the value associated with a LOB expression. For example, a LOB
locator might represent the value associated with: </p>
<pre class="xmp"> <span class="bold">SUBSTR</span>(lob_value_1 <span class="bold">CONCAT</span> lob_value_2 <span class="bold">CONCAT</span> lob_value_3, 42, 6000000)</pre>
<p>For non-locator-based host variables in an application program,
when a null value is selected into that host variable, the indicator variable
is set to -1, signifying that the value is null. In the case of LOB locators,
however, the meaning of indicator variables is slightly different. Since a
LOB locator host variable itself can never be null, a negative indicator variable
value indicates that the LOB value represented by the LOB locator is null.
The null information is kept local to the client by virtue of the indicator
variable value -- the server does not track null values with valid LOB locators.</p>
<p>It is important to understand that a LOB locator represents a value, not
a row or location in the database. Once a value is selected into a LOB locator,
there is no operation that one can perform on the original row or table that
will affect the value which is referenced by the LOB locator. The value associated
with a LOB locator is valid until the transaction ends, or until the LOB locator
is explicitly freed, whichever comes first.</p>
<p>A LOB locator is only a mechanism used to refer to a LOB value during a
transaction; it does not persist beyond the transaction in which it was created.
Also, it is not a database type; it is never stored in the database and, as
a result, cannot participate in views or check constraints. However, since
a locator is a representation of a LOB type, there are SQLTYPEs for LOB locators
so that they can be described within an SQLDA structure that is used by FETCH,
OPEN, CALL, and EXECUTE statements.</p>
<p>For the restrictions that apply to the use of LOB strings, see <a href="rbafzmstch2data.htm#limstr">Limitations on use of strings</a>.</p>
<a name="limstr"></a>
<h3 id="limstr"><a href="rbafzmst02.htm#ToC_123">Limitations on use of strings</a></h3><a id="idx374" name="idx374"></a>
<p>The following varying-length string data types cannot be referenced in
certain contexts: </p>
<ul>
<li>for character strings, any CLOB string</li>
<li>for graphic strings, any DBCLOB string</li>
<li>for binary strings, any BLOB string.</li></ul><p class="indatacontent"> </p>
<a name="wq94"></a>
<table id="wq94" width="100%" summary="" border="1" frame="hsides" rules="rows">
<caption>Table 4. Contexts for limitations on use of varying-length strings</caption>
<thead valign="bottom">
<tr>
<th id="wq95" width="50%" align="left" valign="top">Context of usage</th>
<th id="wq96" width="50%" align="left" valign="top">LOB (CLOB, DBCLOB, or BLOB)</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td valign="top" headers="wq95">A GROUP BY clause</td>
<td valign="top" headers="wq96">Not allowed</td>
</tr>
<tr>
<td valign="top" headers="wq95">An ORDER BY clause</td>
<td valign="top" headers="wq96">Not allowed</td>
</tr>
<tr>
<td valign="top" headers="wq95">A CREATE INDEX statement</td>
<td valign="top" headers="wq96">Not allowed</td>
</tr>
<tr>
<td valign="top" headers="wq95">A SELECT DISTINCT statement</td>
<td valign="top" headers="wq96">Not allowed</td>
</tr>
<tr>
<td valign="top" headers="wq95">A subselect of a UNION, EXCEPT, or INTERSECT without the
ALL keyword</td>
<td valign="top" headers="wq96">Not allowed</td>
</tr>
<tr>
<td valign="top" headers="wq95">The definition of primary, unique, and foreign keys</td>
<td valign="top" headers="wq96">Not allowed</td>
</tr>
<tr>
<td valign="top" headers="wq95">Parameters of built-in functions</td>
<td valign="top" headers="wq96">Some functions that allow varying-length character strings,
varying-length graphic strings, or both types of strings as input arguments
do not support CLOB or DBCLOB strings, or both as input. See the description
of the individual functions in <a href="rbafzmstch2func.htm#ch2func">Built-in functions</a> for the data types that
are allowed as input to each function.</td>
</tr>
</tbody>
</table>
<a name="ch2datetime"></a>
<h3 id="ch2datetime"><a href="rbafzmst02.htm#ToC_124">Datetime values</a></h3><a id="idx375" name="idx375"></a><a id="idx376" name="idx376"></a><a id="idx377" name="idx377"></a>
<p>Although datetime values can be used in certain arithmetic and string operations
and are compatible with certain strings, they are neither strings nor numbers.
However, strings can represent datetime values; see <a href="rbafzmstch2data.htm#dtstrng">String representations of datetime values</a>.</p>
<a name="wq97"></a>
<h4 id="wq97">Date</h4><a id="idx378" name="idx378"></a>
<p>A <span class="italic">date</span> is a three-part value (year, month, and day) designating a point
in time under the Gregorian calendar<sup class="fn"><a href="rbafzmstch2data.htm#fn11">20</a></sup>, which is assumed
to have been in effect from the year 1 A.D. The range of the year part is
0001 to 9999. The date formats *JUL, *MDY, *DMY, and *YMD can only represent
dates in the range 1940 through 2039. The range of the month part is 1 to
12. The range of the day part is 1 to <var class="pv">x</var>, where <var class="pv">x</var> is 28,
29, 30, or 31, depending on the month and year.</p>
<p>The internal representation of a date is a string of 4 bytes that contains
an integer. The integer (called the Scaliger number) represents the date.</p>
<p>The length of a DATE column as described in the SQLDA is 6, 8, or 10 bytes,
depending on which format is used. These are the appropriate lengths for string
representations for the value.</p>
<a name="wq98"></a>
<h4 id="wq98">Time</h4><a id="idx379" name="idx379"></a>
<p>A <span class="italic">time</span> is a three-part value (hour, minute, and
second) designating a time of day using a 24-hour clock. The range of the
hour part is 0 to 24, while the range of the minute and second parts is 0
to 59. If the hour is 24, the minute and second specifications are both zero.</p>
<p>The internal representation of a time is a string of 3 bytes. Each byte
consists of two packed decimal digits. The first byte represents the hour,
the second byte the minute, and the last byte the second.</p>
<p>The length of a TIME column as described in the SQLDA is 8 bytes, which
is the appropriate length for a string representation of the value.</p>
<a name="wq99"></a>
<h4 id="wq99">Timestamp</h4><a id="idx380" name="idx380"></a>
<p>A <span class="italic">timestamp</span> is a seven-part value (year, month,
day, hour, minute, second, and microsecond) that designates a date and time
as defined previously, except that the time includes a fractional specification
of microseconds.</p>
<p>The internal representation of a timestamp is a string of 10 bytes. The
first 4 bytes represent the date, the next 3 bytes the time, and the last
3 bytes the microseconds (the last 3 bytes contain 6 packed digits).</p>
<p>The length of a TIMESTAMP column as described in the SQLDA is 26 bytes,
which is the appropriate length for the string representation of the value.</p>
<a name="wq100"></a>
<h4 id="wq100">Datetime variables</h4>
<p>Character string variables are normally used to contain date, time, and
timestamp values. However, date, time, and timestamp variables can also be
specified in ILE COBOL and ILE RPG. Date, time, and timestamp variables can
also be specified in Java as java.sql.Date, java.sql.Time, and
java.sql.Timestamp respectively.</p>
<a name="dtstrng"></a>
<h4 id="dtstrng">String representations of datetime values</h4><a id="idx381" name="idx381"></a><a id="idx382" name="idx382"></a><a id="idx383" name="idx383"></a>
<p>Values whose data types are DATE, TIME, or TIMESTAMP are represented in
an internal form that is transparent to the user of SQL. Dates, times, and
timestamps, however, can also be represented by character or UTF-16 or UCS-2
graphic strings. Only ILE RPG and ILE COBOL support datetime variables. To be
retrieved, a datetime value can be assigned to a string variable. The format
of the resulting string will depend on the default date format and the default
time format in effect when the statement was prepared. The default date and
time formats are set based on the date format (DATFMT), the date separator
(DATSEP), the time format (TIMFMT), and the time separator (TIMSEP) parameters.</p>
<p>When a valid string representation of a datetime value is used in an operation
with an internal datetime value, the string representation is converted to
the internal form of the date, time, or timestamp before the operation is
performed. If the CCSID of the string represents a foreign encoding scheme
(for example, ASCII), it is first converted to the coded character set identified
by the default CCSID before the string is converted to the internal form of
the datetime value.</p>
<p>The following sections define the valid string representations of datetime
values.</p>
<a name="wq101"></a>
<h5 id="wq101">Date strings</h5>
<p>A string representation of a date is a character or a UCS-2
or UTF-16 graphic string that starts with a digit and has a length of at least
6 characters. Trailing blanks can be included. Leading zeros can be omitted
from the month and day portions when using the IBM&reg; SQL standard formats. Each IBM SQL standard
format is identified by name and includes an associated abbreviation (for
use by the CHAR function). Other formats do not have an abbreviation to be
used by the CHAR function. The separators for two-digit year formats are
controlled by the date separator (DATSEP) parameter. Valid string formats
for dates are listed in <a href="rbafzmstch2data.htm#datstt1">Table 5</a>.</p>
<p>The database manager recognizes the string as a date when it is either: </p>
<ul>
<li>In the format specified by the default date format, or</li>
<li>In the ANSI/ISO SQL standard date format, or</li>
<li>In one of the IBM SQL standard date formats, or</li>
<li>In the unformatted Julian format</li></ul><a id="idx384" name="idx384"></a><a id="idx385" name="idx385"></a><a id="idx386" name="idx386"></a><a id="idx387" name="idx387"></a><a id="idx388" name="idx388"></a><a id="idx389" name="idx389"></a><a id="idx390" name="idx390"></a><a id="idx391" name="idx391"></a><a id="idx392" name="idx392"></a><a id="idx393" name="idx393"></a><a id="idx394" name="idx394"></a><a id="idx395" name="idx395"></a><a id="idx396" name="idx396"></a><a id="idx397" name="idx397"></a><a id="idx398" name="idx398"></a><a id="idx399" name="idx399"></a><a id="idx400" name="idx400"></a><a id="idx401" name="idx401"></a><a id="idx402" name="idx402"></a><a id="idx403" name="idx403"></a>
<a name="datstt1"></a>
<table id="datstt1" width="100%" summary="" border="1" frame="hsides" rules="rows">
<caption>Table 5. Formats for String Representations of Dates</caption>
<thead valign="bottom">
<tr>
<th id="wq102" width="40%" align="left" valign="bottom">Format Name</th>
<th id="wq103" width="20%" align="left" valign="bottom">Abbreviation</th>
<th id="wq104" width="20%" align="left" valign="bottom">Date Format</th>
<th id="wq105" width="20%" align="left" valign="bottom">Example</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq102">ANSI/ISO SQL standard date format (&ndash;)</td>
<td align="left" valign="top" headers="wq103">&ndash;</td>
<td align="left" valign="top" headers="wq104">DATE 'yyyy-mm-dd'</td>
<td align="left" valign="top" headers="wq105">DATE '1987-10-12'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">International Standards Organization (*ISO)</td>
<td align="left" valign="top" headers="wq103">ISO</td>
<td align="left" valign="top" headers="wq104">'yyyy-mm-dd'</td>
<td align="left" valign="top" headers="wq105">'1987-10-12'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">IBM USA standard (*USA)</td>
<td align="left" valign="top" headers="wq103">USA</td>
<td align="left" valign="top" headers="wq104">'mm/dd/yyyy'</td>
<td align="left" valign="top" headers="wq105">'10/12/1987'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">IBM European standard (*EUR)</td>
<td align="left" valign="top" headers="wq103">EUR</td>
<td align="left" valign="top" headers="wq104">'dd.mm.yyyy'</td>
<td align="left" valign="top" headers="wq105">'12.10.1987'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">Japanese industrial standard Christian era
(*JIS)</td>
<td align="left" valign="top" headers="wq103">JIS</td>
<td align="left" valign="top" headers="wq104">'yyyy-mm-dd'</td>
<td align="left" valign="top" headers="wq105">'1987-10-12'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">Unformatted Julian</td>
<td align="left" valign="top" headers="wq103">&ndash;</td>
<td align="left" valign="top" headers="wq104">'yyyyddd'</td>
<td align="left" valign="top" headers="wq105">'1987285'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">Julian (*JUL)</td>
<td align="left" valign="top" headers="wq103">&ndash;</td>
<td align="left" valign="top" headers="wq104">'yy/ddd'</td>
<td align="left" valign="top" headers="wq105">'87/285'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">Month, day, year (*MDY)</td>
<td align="left" valign="top" headers="wq103">&ndash;</td>
<td align="left" valign="top" headers="wq104">'mm/dd/yy'</td>
<td align="left" valign="top" headers="wq105">'10/12/87'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">Day, month, year (*DMY)</td>
<td align="left" valign="top" headers="wq103">&ndash;</td>
<td align="left" valign="top" headers="wq104">'dd/mm/yy'</td>
<td align="left" valign="top" headers="wq105">'12/10/87'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq102">Year, month, day (*YMD)</td>
<td align="left" valign="top" headers="wq103">&ndash;</td>
<td align="left" valign="top" headers="wq104">'yy/mm/dd'</td>
<td align="left" valign="top" headers="wq105">'87/12/10'</td>
</tr>
</tbody>
</table>
<p>The default date format can be specified through the following interfaces:
<a id="idx404" name="idx404"></a><a id="idx405" name="idx405"></a></p>
<a name="dftcol1a"></a>
<table id="dftcol1a" width="100%" summary="" border="1" frame="hsides" rules="rows">
<caption>Table 6. Default Date Format Interfaces</caption>
<thead valign="bottom">
<tr>
<th id="wq106" width="40%" align="left" valign="bottom">SQL Interface</th>
<th id="wq107" width="60%" align="left" valign="bottom">Specification</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq106">Embedded SQL</td>
<td align="left" valign="top" headers="wq107">The DATFMT and DATSEP parameters are specified
on the Create SQL Program (CRTSQLxxx) commands. The SET OPTION statement can
also be used to specify the DATFMT and DATSEP parameters within the source
of a program containing embedded SQL.
<div class="lines"><br />
</div>(For more information
about CRTSQLxxx commands, see the <a href="../rzajp/rzajpkickoff.htm">Embedded SQL Programming</a> book.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq106">Interactive SQL and Run SQL Statements</td>
<td align="left" valign="top" headers="wq107">The DATFMT and DATSEP parameters on the Start
SQL (STRSQL) command or by changing the session attributes. The DATFMT and
DATSEP parameters on the Run SQL Statements (RUNSQLSTM) command.
<div class="lines"><br />
</div>(For
more information about STRSQL and RUNSQLSTM commands, see the <a href="../sqlp/rbafykickoff.htm">SQL Programming</a> book.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq106">Call Level Interface (CLI) on the server</td>
<td align="left" valign="top" headers="wq107">SQL_ATTR_DATE_FMT and SQL_ATTR_DATE_SEP environment
or connection variables
<div class="lines"><br />
</div>(For more information about CLI, see
the <a href="../cli/rzadpkickoff.htm">SQL Call Level Interfaces (ODBC)</a> book.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq106">JDBC or SQLJ on the server using IBM Developer Kit for Java</td>
<td align="left" valign="top" headers="wq107">Date Format and Date Separator connection
property
<div class="lines"><br />
</div>(For more information about JDBC and SQLJ, see the <a href="../rzaha/whatitis.htm">IBM Developer Kit for Java</a> topic in the iSeries Information Center.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq106">ODBC on a client using the iSeries Access Family ODBC Driver</td>
<td align="left" valign="top" headers="wq107">Date Format and Date Separator in the Advanced
Server Options in ODBC Setup
<div class="lines"><br />
</div>(For more information about ODBC,
see the <a href="../rzahg/rzahgicia.htm">iSeries&trade; Access</a> category in the iSeries Information Center.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq106">JDBC on a client using the IBM Toolbox for Java</td>
<td align="left" valign="top" headers="wq107">Format in JDBC Setup
<div class="lines"><br />
</div>(For
more information about ODBC, see the <a href="../rzahg/rzahgicia.htm">iSeries Access</a> category
in the iSeries Information Center.)
<div class="lines"><br />
</div>(For more information about the IBM Toolbox for Java,
see <a href="../rzahh/page1.htm">IBM Toolbox for Java</a> topic in the iSeries Information Center .)</td>
</tr>
</tbody>
</table>
<a name="wq108"></a>
<h5 id="wq108">Time strings</h5>
<p>A string representation of a time is a character or a UCS-2
or UTF-16 graphic string that starts with a digit and has a length of at least
4 characters. Trailing blanks can be included; a leading zero can be omitted
from the hour part of the time and seconds can be omitted entirely. If you
choose to omit seconds, an implicit specification of 0 seconds is assumed.
Thus, 13.30 is equivalent to 13.30.00.</p>
<p>Valid string formats for times are listed in <a href="rbafzmstch2data.htm#timstt1">Table 7</a>. Each IBM SQL
standard format is identified by name and includes an associated abbreviation
(for use by the CHAR function). The other format (*HMS) does not have an abbreviation
to be used by the CHAR function. The separator for the *HMS format is controlled
by the time separator (TIMSEP) parameter.</p>
<p>The database manager recognizes the string as a time when it is either: </p>
<ul>
<li>In the format specified by the default time format, or</li>
<li>In the ANSI/ISO SQL standard time format, or</li>
<li>In one of the IBM SQL standard time formats</li></ul><a id="idx406" name="idx406"></a><a id="idx407" name="idx407"></a><a id="idx408" name="idx408"></a><a id="idx409" name="idx409"></a><a id="idx410" name="idx410"></a><a id="idx411" name="idx411"></a><a id="idx412" name="idx412"></a><a id="idx413" name="idx413"></a><a id="idx414" name="idx414"></a><a id="idx415" name="idx415"></a>
<a name="timstt1"></a>
<table id="timstt1" width="100%" summary="" border="1" frame="hsides" rules="rows">
<caption>Table 7. Formats for String Representations of Times</caption>
<thead valign="bottom">
<tr>
<th id="wq109" width="40%" align="left" valign="bottom">Format Name</th>
<th id="wq110" width="20%" align="left" valign="bottom">Abbreviation</th>
<th id="wq111" width="20%" align="left" valign="bottom">Time Format</th>
<th id="wq112" width="20%" align="left" valign="bottom">Example</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq109">ANSI/ISO SQL standard time format (&ndash;)</td>
<td align="left" valign="top" headers="wq110">&ndash;</td>
<td align="left" valign="top" headers="wq111">TIME 'hh:mm:ss'</td>
<td align="left" valign="top" headers="wq112">TIME '13:30:05'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq109">International Standards Organization (*ISO)</td>
<td align="left" valign="top" headers="wq110">ISO</td>
<td align="left" valign="top" headers="wq111">'hh.mm.ss' <sup class="fn"><a href="rbafzmstch2data.htm#isofm">21</a></sup></td>
<td align="left" valign="top" headers="wq112">'13.30.05'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq109">IBM USA standard (*USA)</td>
<td align="left" valign="top" headers="wq110">USA</td>
<td align="left" valign="top" headers="wq111">'hh:mm AM' (or PM)</td>
<td align="left" valign="top" headers="wq112">'1:30 PM'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq109">IBM European standard (*EUR)</td>
<td align="left" valign="top" headers="wq110">EUR</td>
<td align="left" valign="top" headers="wq111">'hh.mm.ss'</td>
<td align="left" valign="top" headers="wq112">'13.30.05'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq109">Japanese industrial standard Christian era
(*JIS)</td>
<td align="left" valign="top" headers="wq110">JIS</td>
<td align="left" valign="top" headers="wq111">'hh:mm:ss'</td>
<td align="left" valign="top" headers="wq112">'13:30:05'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq109">Hours, minutes, seconds (*HMS)</td>
<td align="left" valign="top" headers="wq110">&ndash;</td>
<td align="left" valign="top" headers="wq111">'hh:mm:ss'</td>
<td align="left" valign="top" headers="wq112">'13:30:05'</td>
</tr>
</tbody>
</table>
<p>The following additional rules apply to the USA time format:</p>
<ul>
<li>The hour must not be greater than 12 and cannot be 0 except for the special
case of 00:00 AM.</li>
<li>A single space character exists between the minutes portion of the time
of day and the AM or PM.</li>
<li>The minutes can be omitted entirely. If you choose to omit the minutes,
an implicit specification of 0 minutes is assumed.</li></ul><p class="indatacontent"> In the USA format, using the ISO format of the 24-hour clock, the correspondence
between the USA format and the 24-hour clock is as follows:</p>
<a name="wq113"></a>
<table id="wq113" width="100%" summary="" border="0" frame="void" rules="none">
<caption>Table 8. USA Time Format</caption>
<thead valign="bottom">
<tr>
<th id="wq114" width="50%" align="left" valign="top"><span class="bold">USA Format</span></th>
<th id="wq115" width="50%" align="left" valign="top"><span class="bold">24-Hour Clock</span></th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq114">12:01 AM through 12:59 AM</td>
<td align="left" valign="top" headers="wq115">00.01.00 through 00.59.00</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq114">01:00 AM through 11:59 AM</td>
<td align="left" valign="top" headers="wq115">01:00.00 through 11:59.00</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq114">12:00 PM (noon) through 11:59 PM</td>
<td align="left" valign="top" headers="wq115">12:00.00 through 23.59.00</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq114">12:00 AM (midnight)</td>
<td align="left" valign="top" headers="wq115">24.00.00</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq114">00:00 AM (midnight)</td>
<td align="left" valign="top" headers="wq115">00.00.00</td>
</tr>
</tbody>
</table>
<p>The default time format can be specified through the following interfaces:
<a id="idx416" name="idx416"></a><a id="idx417" name="idx417"></a></p>
<a name="dftcol1c"></a>
<table id="dftcol1c" width="100%" summary="" border="1" frame="hsides" rules="rows">
<caption>Table 9. Default Time Format Interfaces</caption>
<thead valign="bottom">
<tr>
<th id="wq116" width="40%" align="left" valign="bottom">SQL Interface</th>
<th id="wq117" width="60%" align="left" valign="bottom">Specification</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq116">Embedded SQL</td>
<td align="left" valign="top" headers="wq117">The TIMFMT and TIMSEP parameters are specified
on the Create SQL Program (CRTSQLxxx) commands. The SET OPTION statement can
also be used to specify the TIMFMT and TIMSEP parameters within the source
of a program containing embedded SQL.
<div class="lines"><br />
</div>(For more information
about CRTSQLxxx commands, see the <a href="../rzajp/rzajpkickoff.htm">Embedded SQL Programming</a> book.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq116">Interactive SQL and Run SQL Statements</td>
<td align="left" valign="top" headers="wq117">The TIMFMT and TIMSEP parameters on the Start
SQL (STRSQL) command or by changing the session attributes. The TIMFMT and
TIMSEP parameters on the Run SQL Statements (RUNSQLSTM) command.
<div class="lines"><br />
</div>(For
more information about STRSQL and RUNSQLSTM commands, see the <a href="../sqlp/rbafykickoff.htm">SQL Programming</a> book.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq116">Call Level Interface (CLI) on the server</td>
<td align="left" valign="top" headers="wq117">SQL_ATTR_TIME_FMT and SQL_ATTR_TIME_SEP environment
or connection variables
<div class="lines"><br />
</div>(For more information about CLI, see
the <a href="../cli/rzadpkickoff.htm">SQL Call Level Interfaces (ODBC)</a> book.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq116">JDBC or SQLJ on the server using IBM Developer Kit for Java</td>
<td align="left" valign="top" headers="wq117">Time Format and Time Separator connection
property object
<div class="lines"><br />
</div>(For more information about JDBC and SQLJ, see
the <a href="../rzaha/whatitis.htm">IBM Developer Kit for Java</a> topic in the iSeries Information Center.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq116">ODBC on a client using the iSeries Access Family ODBC Driver</td>
<td align="left" valign="top" headers="wq117">Time Format and Time Separator in the Advanced
Server Options in ODBC Setup
<div class="lines"><br />
</div>(For more information about ODBC,
see the <a href="../rzahg/rzahgicia.htm">iSeries Access Family </a> category in the iSeries Information Center.)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq116">JDBC on a client using the IBM Toolbox for Java</td>
<td align="left" valign="top" headers="wq117">Format in JDBC Setup
<div class="lines"><br />
</div>(For
more information about the IBM Toolbox for Java, see <a href="../rzahh/page1.htm">IBM Toolbox for Java</a> topic in the iSeries Information Center .)</td>
</tr>
</tbody>
</table>
<a name="wq118"></a>
<h5 id="wq118">Timestamp strings</h5><a id="idx418" name="idx418"></a>
<p>A string representation of a timestamp is a character or a UCS-2 or UTF-16
graphic string that starts with a digit and has a length of at least 16 characters.
The complete string representation of a timestamp has one of the following
forms:</p>
<a name="timstt2"></a>
<table id="timstt2" width="100%" summary="" border="1" frame="hsides" rules="rows">
<caption>Table 10. Formats for String Representations of Timestamps</caption>
<thead valign="bottom">
<tr>
<th id="wq119" width="19%" align="left" valign="bottom">Format Name</th>
<th id="wq120" width="40%" align="left" valign="bottom">Time Format</th>
<th id="wq121" width="40%" align="left" valign="bottom">Example</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq119">ANSI/ISO SQL standard</td>
<td align="left" valign="top" headers="wq120">TIMESTAMP 'yyyy-mm-dd hh:mm:ss.nnnnnn'</td>
<td align="left" valign="top" headers="wq121">TIMESTAMP '1990-03-02 08:30:00.010000'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq119">ISO timestamp</td>
<td align="left" valign="top" headers="wq120">'yyyy-mm-dd hh:mm:ss.nnnnnn'</td>
<td align="left" valign="top" headers="wq121">'1990-03-02 08:30:00.010000'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq119">IBM SQL</td>
<td align="left" valign="top" headers="wq120">'yyyy-mm-dd-hh.mm.ss.nnnnnn'</td>
<td align="left" valign="top" headers="wq121">'1990-03-02-08.30.00.010000'</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq119">14&ndash;character form</td>
<td align="left" valign="top" headers="wq120">'yyyymmddhhmmss'</td>
<td align="left" valign="top" headers="wq121">'19900302083000'</td>
</tr>
</tbody>
</table><p class="indatacontent">Trailing blanks can be included. Leading zeros can be omitted from
the month, day, and hour part of the timestamp when using the timestamp form
with separators. Trailing zeros can be truncated or omitted entirely from
microseconds. If you choose to omit any digit of the microseconds portion,
an implicit specification of 0 is assumed. Thus, <span class="italic">1990-3-2-8.30.00.10</span> is equivalent to <span class="italic">1990-03-02-08.30.00.100000</span>.</p>
<p>A timestamp whose time part is 24.00.00.000000 is also accepted.</p>
<a name="ch2datalink"></a>
<h3 id="ch2datalink"><a href="rbafzmst02.htm#ToC_133">DataLink values</a></h3>
<p><a id="idx419" name="idx419"></a><a id="idx420" name="idx420"></a></p>
<p>A DataLink value is an encapsulated value that contains a logical reference
from the database to a file stored outside the database. The attributes of
this encapsulated value are as follows:</p>
<dl>
<dt class="bold">link type</dt>
<dd>The currently supported type of link is a URL (Uniform Resource Locator).
</dd>
<dt class="bold">scheme</dt>
<dd>For URLs, this is a value such as HTTP or FILE. The value, no matter
what case it is entered in, is stored in the database in upper case.
</dd>
<dt class="bold">file server name</dt>
<dd>The complete address of the file server. The value, no matter what case
it is entered in, is stored in the database in upper case.
</dd>
<dt class="bold">file path</dt>
<dd>The identity of the file within the server. The value is case sensitive
and therefore it is not converted to upper case when stored in the database.
</dd>
<dt class="bold">access control token</dt>
<dd>When appropriate, the access token is embedded within the file path.
It is generated dynamically and is not a permanent part of the DataLink value
that is stored in the database.
</dd>
<dt class="bold">comment</dt>
<dd>Up to 254 bytes of descriptive information. This is intended for application
specific uses such as further or alternative identification of the location
of the data.
</dd>
</dl>
<p>The characters used in a DataLink value are limited to the set defined
for a URL. These characters include the uppercase (A through Z) and lower
case (a through z) letters, the digits (0 through 9) and a subset of special
characters ($, -, _, @, ., &amp;, +, !, *, ", ', (, ), =, ;, /, #, ?, :, space,
and comma).</p>
<p>The first four attributes are collectively known as the linkage attributes.
It is possible for a DataLink value to have only a comment attribute and no
linkage attributes. Such a value may even be stored in a column but, of course,
no file will be linked to such a column.</p>
<p>It is important to distinguish between these DataLink references to files
and the LOB file reference variables described in <a href="rbafzmstch2refvar.htm#rlobref">References to LOB file reference variables</a>.
The similarity is that they both contain a representation of a file. However: </p>
<ul>
<li>DataLinks are retained in the database and both the links and the data
in the linked files can be considered as a natural extension of data in the
database.</li>
<li>File reference variables exist temporarily and they can be considered
as an alternative to a host program buffer.</li></ul>
<p>Built-in scalar functions are provided to build a DataLink value (DLVALUE)
and to extract the encapsulated values from a DataLink value (DLCOMMENT, DLLINKTYPE,
DLURLCOMPLETE, DLURLPATH, DLURLPATHONLY, DLURLSCHEME, DLURLSERVER).</p>
<a name="ch2rowid"></a>
<h3 id="ch2rowid"><a href="rbafzmst02.htm#ToC_134">Row ID values</a></h3>
<p><a id="idx421" name="idx421"></a><a id="idx422" name="idx422"></a>A <span class="italic">row ID</span> is a value that
uniquely identifies a row in a table. A column or a variable can have a row
ID data type. A ROWID column enables queries to be written that navigate directly
to a row in the table. Each value in a ROWID column must be unique. The database manager maintains
the values permanently, even across table reorganizations. When a row is inserted
into the table, the database manager generates a value for the ROWID column unless one
is supplied. If a value is supplied, it must be a valid row ID value that
was previously generated by either DB2 UDB for z/OS or DB2 UDB for iSeries.</p>
<p>The internal representation of a row ID value is transparent to the user.
The value is never subject to CCSID conversion because it is considered to
contain BIT data. The length attribute of a ROWID column is 40.</p>
<a name="ch2udf"></a>
<h3 id="ch2udf"><a href="rbafzmst02.htm#ToC_135">User-defined types</a></h3>
<p><a id="idx423" name="idx423"></a><a id="idx424" name="idx424"></a></p>
<a name="wq122"></a>
<h4 id="wq122">Distinct types</h4><a id="idx425" name="idx425"></a><a id="idx426" name="idx426"></a>
<p>A <span class="italic">distinct type</span> is a user-defined data type that
shares its internal representation with a built-in data type (its "source
type"), but is considered to be a separate and incompatible type for most
operations. For example, the semantics for a picture type, a text type, and
an audio type that all use the built-in data type BLOB for their internal
representation are quite different. A distinct type is created using <a href="rbafzmstcrtudt.htm#crtudt">CREATE DISTINCT TYPE</a>.</p>
<p>For example, the following statement creates a distinct type named AUDIO:</p>
<pre class="xmp"> <span class="bold">CREATE DISTINCT TYPE</span> AUDIO <span class="bold">AS BLOB</span> (1M)
</pre>
<p>Although AUDIO has the same representation as the built-in data type BLOB,
it is considered to be a separate type that is not comparable to a BLOB or
to any other type. This inability to compare AUDIO to other data types allows
functions to be created specifically for AUDIO and assures that these functions
cannot be applied to other data types (such as pictures or text).</p>
<p>The name of a distinct type is qualified with a schema name. The implicit
schema name for an unqualified name depends upon the context in which the
distinct type appears. If an unqualified distinct type name is used: </p>
<ul>
<li>In a CREATE DISTINCT TYPE or the object of DROP, COMMENT, GRANT, or REVOKE
statement, the database manager uses the normal process of qualification by authorization
ID to determine the schema name. For more information about qualification
rules, see <a href="rbafzmstch2nam.htm#qualun2">Unqualified function, procedure, specific, and distinct type names</a>.</li>
<li>In any other context, the database manager uses the SQL path to determine the schema
name. The database manager searches the schemas in the path, in sequence,
and selects the first schema that has a distinct type that matches. For a
description of the SQL path, see <a href="rbafzmstspecreg.htm#curpath">CURRENT PATH</a>.</li></ul>
<p>A distinct type does not automatically acquire the functions and operators
of its source type, since these may not be meaningful. (For example, the LENGTH
function of the AUDIO type might return the length of its object in seconds
rather than in bytes.) Instead, distinct types support <span class="italic">strong typing</span>. Strong typing ensures that only the functions and operators
that are explicitly defined for a distinct type can be applied to that distinct
type. However, a function or operator of the source type can be applied to
the distinct type by creating an appropriate user-defined function. The user-defined
function must be sourced on the existing function that has the source type
as a parameter. For example, the following series of SQL statements shows
how to create a distinct type named MONEY based on data type DECIMAL(9,2),
how to define the + operator for the distinct type, and how the operator might
be applied to the distinct type: </p>
<pre class="xmp"><span class="bold">CREATE DISTINCT TYPE</span> MONEY <span class="bold">AS DECIMAL(9,2) WITH COMPARISONS</span>
<span class="bold">CREATE FUNCTION</span> "+"(MONEY,MONEY)
<span class="bold">RETURNS</span> MONEY
<span class="bold">SOURCE</span> "+"(DECIMAL(9,2),DECIMAL(9,2))
<span class="bold">CREATE TABLE</span> SALARY_TABLE
(SALARY MONEY,
COMMISSION MONEY)
<span class="bold">SELECT</span> "+"(SALARY, COMMISSION) <span class="bold">FROM</span> SALARY_TABLE</pre>
<p>A distinct type is subject to the same restrictions as its source type.
For example, a table can only have one ROWID column. Therefore, a table with
a ROWID column cannot also have a column with distinct type that is sourced
on a row ID.</p>
<p>The comparison operators are automatically generated for distinct types,
except for distinct types that are sourced on a DataLink. In addition, the database manager automatically
generates functions for a distinct type that support casting from the source
type to the distinct type and from the distinct type to the source type. For
example, for the AUDIO type created above, these are the generated cast functions:
</p>
<a name="wq123"></a>
<table id="wq123" width="100%" summary="" border="0" frame="void" rules="none">
<thead valign="bottom">
<tr>
<th id="wq124" width="33%" align="left">Name of generated cast function</th>
<th id="wq125" width="33%" align="left">Parameter list</th>
<th id="wq126" width="33%" align="left">Returns data type</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td headers="wq124">schema-name.BLOB</td>
<td headers="wq125">schema-name.AUDIO</td>
<td headers="wq126">BLOB</td>
</tr>
<tr>
<td headers="wq124">schema-name.AUDIO</td>
<td headers="wq125">BLOB</td>
<td headers="wq126">schema-name.AUDIO</td>
</tr>
</tbody>
</table>
<hr /><div class="fnnum"><a id="wq93" name="wq93" href="rbafzmstch2data.htm#wq92">19</a>.</div>
<div class="fntext">There is no ability
within a Java&trade; application to distinguish between a CLOB or BLOB
that is represented by a LOB locator and one that is not.</div><div class="fnnum"><a id="fn11" name="fn11">20</a>.</div>
<div class="fntext">Note that historical dates do not always follow the Gregorian
calendar. Dates between 1582-10-04 and 1582-10-15 are accepted as valid dates
although they never existed in the Gregorian calendar.</div><div class="fnnum"><a id="isofm" name="isofm">21</a>.</div>
<div class="fntext">This is an earlier version of the ISO format. JIS can be used
to get the current ISO format.</div>
<br />
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