192 lines
11 KiB
HTML
192 lines
11 KiB
HTML
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<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="dc.language" scheme="rfc1766" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<meta name="dc.date" scheme="iso8601" content="2005-09-19" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="security" content="public" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="keywords" content="SET TRANSACTION statement, SET TRANSACTION,
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SQL statements, set using SET TRANSACTION, isolation level, NO COMMIT clause,
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ISOLATION LEVEL clause, READ UNCOMMITTED clause, READ COMMITTED clause,
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REPEATABLE READ clause, SERIALIZABLE clause, setting isolation level, trigger,
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effect on SET TRANSACTION, COMMIT, ROLLBACK" />
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<title>SET TRANSACTION</title>
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<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
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<link rel="stylesheet" type="text/css" href="ic.css" />
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</head>
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<body>
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<a id="Top_Of_Page" name="Top_Of_Page"></a><!-- Java sync-link -->
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<script language = "Javascript" src = "../rzahg/synch.js" type="text/javascript"></script>
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<a name="settraj"></a>
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<h2 id="settraj"><a href="rbafzmst02.htm#ToC_1348">SET TRANSACTION</a></h2><a id="idx3212" name="idx3212"></a><a id="idx3213" name="idx3213"></a><a id="idx3214" name="idx3214"></a>
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<a name="settran"></a>
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<p id="settran">The SET TRANSACTION statement sets the isolation level, read
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only attribute, or diagnostics area size for the current unit of work.</p>
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<a name="wq1795"></a>
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<h3 id="wq1795"><a href="rbafzmst02.htm#ToC_1349">Invocation</a></h3>
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<p>This statement can be embedded within an application program or issued
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interactively. It is an executable statement that can be dynamically prepared.</p>
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<a name="wq1796"></a>
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<h3 id="wq1796"><a href="rbafzmst02.htm#ToC_1350">Authorization</a></h3>
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<p>None required.</p>
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<a name="wq1797"></a>
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<h3 id="wq1797"><a href="rbafzmst02.htm#ToC_1351">Syntax</a></h3>
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<a href="rbafzmstsettraj.htm#synsst"><img src="c.gif" alt="Click to skip syntax diagram" /></a>
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<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn393.htm"
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border="0" /></span><a href="#skipsyn-392"><img src="c.gif" alt="Skip visual syntax diagram"
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border="0" /></a>>>-SET TRANSACTION---------------------------------------------->
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.-,-----------------------------------------.
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V .-SERIALIZABLE-----. | (1)
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>----+-ISOLATION LEVEL--+-NO COMMIT--------+-+-+---------------><
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| +-READ UNCOMMITTED-+ |
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| +-READ COMMITTED---+ |
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| '-REPEATABLE READ--' |
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| .-READ ONLY--. |
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+-+-READ WRITE-+------------------------+
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'-DIAGNOSTICS SIZE--+-<span class="italic">integer</span>--+--------'
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'-<span><span class="italic">variable</span></span>-'
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</pre>
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<a name="skipsyn-392" id="skipsyn-392"></a>
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<a name="wq1798"></a>
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<div class="notelisttitle" id="wq1798">Notes:</div>
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<ol type="1">
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<li>Only one ISOLATION LEVEL clause, one READ WRITE or READ ONLY clause,
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and one DIAGNOSTICS SIZE clause may be specified.</li>
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</ol>
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<a name="synsst"></a>
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<h3 id="synsst"><a href="rbafzmst02.htm#ToC_1352">Description</a></h3>
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<dl class="parml">
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<dt class="bold">ISOLATION LEVEL</dt>
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<dd>Specifies the isolation level of the transaction. If the ISOLATION LEVEL
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clause is not specified, ISOLATION LEVEL SERIALIZABLE is implicit
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<dl class="parml">
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<dt class="bold">NO COMMIT </dt><a id="idx3215" name="idx3215"></a><a id="idx3216" name="idx3216"></a>
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<dd>Specifies isolation level NC (COMMIT(*NONE)).
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</dd>
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<dt class="bold">READ UNCOMMITTED</dt><a id="idx3217" name="idx3217"></a>
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<dd>Specifies isolation level UR (COMMIT(*CHG)).
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</dd>
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<dt class="bold">READ COMMITTED </dt><a id="idx3218" name="idx3218"></a>
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<dd>Specifies isolation level CS (COMMIT(*CS)).
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</dd>
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<dt class="bold">REPEATABLE READ <sup class="fn"><a id="wq1800" name="wq1800" href="rbafzmstsettraj.htm#wq1801">82</a></sup></dt><a id="idx3219" name="idx3219"></a>
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<dd>Specifies isolation level RS (COMMIT(*ALL)).
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</dd>
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<dt class="bold">SERIALIZABLE </dt><a id="idx3220" name="idx3220"></a>
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<dd>Specifies isolation level RR (COMMIT(*RR)).
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</dd>
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</dl>
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</dd>
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<dt class="bold">READ WRITE or READ ONLY</dt>
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<dd>Specifies whether the transaction allows data change operations.
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<dl class="parml">
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<dt class="bold">READ WRITE</dt>
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<dd>Specifies that all SQL operations are allowed. This is the default unless
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ISOLATION LEVEL READ UNCOMMITTED is specified.
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</dd>
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<dt class="bold">READ ONLY</dt>
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<dd>Specifies that only SQL operations that do not change SQL data are allowed.
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If ISOLATION LEVEL READ UNCOMMITTED is specified, this is the default.
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</dd>
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</dl>
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</dd>
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<dt class="bold">DIAGNOSTICS SIZE</dt>
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<dd>Specifies the maximum number of GET DIAGNOSTICS condition areas for
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the current transaction. The GET DIAGNOSTICS <var class="pv">statement-information-item</var> MORE will be set to 'Y' for the current statement if the statement exceeds
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the maximum number of condition areas for the current transaction. The specified
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maximum number of condition areas must be between 1 and 32767.
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<dl class="parml">
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<dt class="bold"><var class="pv">integer</var></dt>
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<dd>An integer constant that specifies the maximum number of condition areas
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for the current transaction.
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</dd>
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<dt class="bold"><var class="pv">variable</var></dt>
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<dd>Identifies a variable which contains the maximum number of condition
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areas for the current transaction. The variable must be a numeric variable
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with a zero scale and must not be followed by an indicator variable.
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</dd>
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</dl>
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</dd>
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</dl>
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<a name="wq1802"></a>
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<h3 id="wq1802"><a href="rbafzmst02.htm#ToC_1353">Notes</a></h3>
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<p><span class="bold">Scope of SET TRANSACTION:</span> The SET TRANSACTION statement
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sets the isolation level for SQL statements for the current activation group
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of the process. If that activation group has commitment control scoped to
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the job, then the SET TRANSACTION statement sets the isolation level of all
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other activation groups with job commit scoping as well.</p>
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<p>If an isolation clause is specified in an SQL statement, that isolation
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level overrides the transaction isolation level and is used for the SQL statement.</p>
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<p>The scope of the SET TRANSACTION statement is based on the context in which
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it is run. If the SET TRANSACTION statement is run in a trigger, the isolation
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level specified applies to all subsequent SQL statements until another SET
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TRANSACTION statement occurs or until the trigger completes, whichever happens
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first. If the SET TRANSACTION statement is run outside a trigger, the isolation
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level specified applies to all subsequent SQL statements (except those statements
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within a trigger that are executed after a SET TRANSACTION statement in the
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trigger) until a COMMIT or ROLLBACK operation occurs.</p>
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<p>For more information about isolation levels, see <a href="rbafzmstisol.htm#isol">Isolation level</a>.</p><a id="idx3221" name="idx3221"></a>
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<p><span class="bold">SET TRANSACTION restrictions:</span> The SET TRANSACTION
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statement can only be executed when it is the first SQL statement in a unit
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of work, unless:</p>
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<ul>
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<li>all previous statements executed in the unit of work are SET TRANSACTION
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statements or statements that are executed under isolation level NC, or</li>
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<li>it is executed in a trigger.</li></ul><p class="indatacontent">In a trigger, SET TRANSACTION with READ ONLY is allowed only on a COMMIT
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boundary. The SET TRANSACTION statement can be executed in a trigger at any
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time, but it is recommended that it be executed as the first statement in
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the trigger. The SET TRANSACTION statement is useful within triggers to set
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the isolation level for SQL statements in the trigger to the same level as
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the application which caused the trigger to be activated.</p>
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<p>A SET TRANSACTION statement is not allowed if the current connection is
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to a remote application server unless it is in a trigger at the current server. Once
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a SET TRANSACTION statement is executed, CONNECT and SET CONNECTION statements
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are not allowed until the unit of work is committed or rolled back.</p><a id="idx3222" name="idx3222"></a><a id="idx3223" name="idx3223"></a>
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<p>The SET TRANSACTION statement has no effect on WITH HOLD cursors that are
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still open when the SET TRANSACTION statement is executed.</p>
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<p><span class="bold">Syntax alternatives:</span> The following keywords are synonyms
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supported for compatibility to prior releases. These keywords are non-standard
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and should not be used:</p>
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<ul>
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<li>The keywords NC or NONE can be used as synonyms for NO COMMIT.</li>
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<li>The keywords UR and CHG can be used as synonyms for READ UNCOMMITTED.</li>
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<li>The keyword CS can be used as a synonym for READ COMMITTED.</li>
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<li>The keywords RS or ALL can be used as synonyms for REPEATABLE READ.</li>
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<li>The keyword RR can be used as a synonym for SERIALIZABLE.</li></ul>
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<a name="wq1803"></a>
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<h3 id="wq1803"><a href="rbafzmst02.htm#ToC_1354">Examples</a></h3>
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<p><span class="italic">Example 1:</span> The following SET TRANSACTION statement
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sets the isolation level to NONE (equivalent to specifying *NONE on the SQL
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precompiler command). </p>
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<pre class="xmp"> EXEC SQL <span class="bold">SET TRANSACTION ISOLATION LEVEL NO COMMIT;</span></pre>
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<p><span class="italic">Example 2:</span> The following SET TRANSACTION statement
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sets the isolation level to SERIALIZABLE. </p>
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<pre class="xmp"> <span class="bold">SET TRANSACTION ISOLATION LEVEL SERIALIZABLE</span></pre>
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<p><a id="idx3224" name="idx3224"></a><a id="idx3225" name="idx3225"></a></p>
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<hr /><div class="fnnum"><a id="wq1801" name="wq1801" href="rbafzmstsettraj.htm#wq1800">82</a>.</div>
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<div class="fntext">REPEATABLE READ is the ISO and ANS standard
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term that corresponds to the isolation level of *ALL for DB2 UDB for iSeries and the isolation
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level of Read Stability (RS) in IBM® SQL. SERIALIZABLE is used in the ISO and
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ANS standard for what IBM SQL calls Repeatable Read (RR).</div>
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<br />
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<hr /><br />
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[ <a href="#Top_Of_Page">Top of Page</a> | <a href="rbafzsetsessionauth.htm">Previous Page</a> | <a href="rbafzmstsettranv.htm">Next Page</a> | <a href="rbafzmst02.htm#wq1">Contents</a> |
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<a href="rbafzmstindex.htm#index">Index</a> ]
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