129 lines
7.2 KiB
HTML
129 lines
7.2 KiB
HTML
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-us">
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<meta name="dc.date" scheme="iso8601" content="2005-09-19" />
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<meta name="keywords" content="SAVEPOINT statement, SAVEPOINT, SQL statements,
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savepoint, in SAVEPOINT statement, savepoint–name, UNIQUE clause" />
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<title>SAVEPOINT</title>
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<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
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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="svpt"></a>
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<h2 id="svpt"><a href="rbafzmst02.htm#ToC_1261">SAVEPOINT</a></h2><a id="idx3098" name="idx3098"></a><a id="idx3099" name="idx3099"></a><a id="idx3100" name="idx3100"></a>
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<p>The SAVEPOINT statement sets a savepoint within a unit of work to identify
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a point in time within the unit of work to which relational database changes
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can be rolled back.</p>
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<a name="wq1719"></a>
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<h3 id="wq1719"><a href="rbafzmst02.htm#ToC_1262">Invocation</a></h3>
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<p>This statement can be embedded in an application program or issued interactively.
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It is an executable statement that can be dynamically prepared.</p>
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<a name="wq1720"></a>
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<h3 id="wq1720"><a href="rbafzmst02.htm#ToC_1263">Authorization</a></h3>
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<p>None required.</p>
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<a name="wq1721"></a>
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<h3 id="wq1721"><a href="rbafzmst02.htm#ToC_1264">Syntax</a></h3>
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<a href="rbafzmstsvpt.htm#synssavep"><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="rbafzmstsyn376.htm"
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border="0" /></span><a href="#skipsyn-375"><img src="c.gif" alt="Skip visual syntax diagram"
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border="0" /></a>>>-SAVEPOINT--<span class="italic">savepoint-name</span>--+--------+------------------------>
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'-UNIQUE-'
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(1)
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.-ON ROLLBACK RETAIN LOCKS--------.
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>--ON ROLLBACK RETAIN CURSORS--+---------------------------------+-><
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</pre>
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<a name="skipsyn-375" id="skipsyn-375"></a>
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<a name="wq1722"></a>
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<div class="notelisttitle" id="wq1722">Notes:</div>
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<ol type="1">
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<li>The ROLLBACK options can be specified in any order.</li>
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</ol>
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<a name="synssavep"></a>
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<h3 id="synssavep"><a href="rbafzmst02.htm#ToC_1265">Description</a></h3>
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<dl class="parml">
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<dt class="bold"><var class="pv">savepoint-name</var> </dt><a id="idx3101" name="idx3101"></a>
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<dd>Identifies a new savepoint.
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</dd>
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<dt class="bold">UNIQUE </dt><a id="idx3102" name="idx3102"></a>
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<dd>Specifies that the application program cannot reuse the savepoint name
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within the unit of work. An error occurs if a savepoint with the same name
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as <var class="pv">savepoint-name</var> already exists within the unit of work.
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<p>Omitting
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UNIQUE indicates that the application can reuse the savepoint name within
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the unit of work. If <var class="pv">savepoint-name</var> identifies a savepoint that already
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exists within the unit of work and the savepoint was not created with the
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UNIQUE option, the existing savepoint is destroyed and a new savepoint is
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created. Destroying a savepoint to reuse its name for another savepoint is
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not the same as releasing the savepoint. Reusing a savepoint name destroys
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only one savepoint. Releasing a savepoint with the RELEASE SAVEPOINT statement
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releases the savepoint and all savepoints that have been subsequently set.</p>
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</dd>
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<dt class="bold">ON ROLLBACK RETAIN CURSORS</dt>
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<dd>Specifies that cursors that are opened after the savepoint is set are
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not closed upon rollback to the savepoint.
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<ul>
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<li>If SQL schema statements are executed for a table or view within
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the scope of the SAVEPOINT statement, any cursor that references that table
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or view is closed. Attempts to use such a cursor after a ROLLBACK TO SAVEPOINT
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results in an error.</li>
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<li>Otherwise, the cursor is not affected by the ROLLBACK TO SAVEPOINT (it
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remains open and positioned).</li></ul>Although these cursors remain open after rollback to the savepoint, they
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might not be usable. For example, if rolling back to the savepoint causes
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the insertion of a row on which the cursor is positioned to be rolled back,
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using the cursor to update or delete the row results in an error.
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</dd>
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<dt class="bold">ON ROLLBACK RETAIN LOCKS</dt>
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<dd>Specifies that any locks that are acquired after the savepoint is set
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are not released on rollback to the savepoint.
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</dd>
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</dl>
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<a name="wq1724"></a>
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<h3 id="wq1724"><a href="rbafzmst02.htm#ToC_1266">Note</a></h3>
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<p><span class="bold">Effect on INSERT:</span> In an application, inserts may
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be buffered. The buffer will be flushed when SAVEPOINT, ROLLBACK, or RELEASE
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TO SAVEPOINT statements are issued.</p>
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<p><span class="bold">SAVEPOINT Restriction:</span> A SAVEPOINT statement is not
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allowed if commitment control is not active for the activation group. For
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information on determining which commitment definition is used, see <a href="rbafzmstc4comit.htm#macomm">Notes</a>.</p>
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<a name="wq1725"></a>
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<h3 id="wq1725"><a href="rbafzmst02.htm#ToC_1267">Example</a></h3>
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<p>Assume that you want to set three savepoints at various points in a unit
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of work. Name the first savepoint A and allow the savepoint name to be reused.
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Name the second savepoint B and do not allow the name to be reused. Because
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you no longer need savepoint A when you are ready to set the third savepoint,
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reuse A as the name of the savepoint.</p>
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<pre class="xmp"> <span class="bold">SAVEPOINT</span> A <span class="bold">ON ROLLBACK RETAIN CURSORS</span>;
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.
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.
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.
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<span class="bold">SAVEPOINT</span> B <span class="bold">UNIQUE ON ROLLBACK RETAIN CURSORS</span>;
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.
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.
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.
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<span class="bold">SAVEPOINT</span> A <span class="bold">ON ROLLBACK RETAIN CURSORS</span>;</pre><a id="idx3103" name="idx3103"></a><a id="idx3104" name="idx3104"></a>
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<hr /><br />
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[ <a href="#Top_Of_Page">Top of Page</a> | <a href="rbafzmstrollbac.htm">Previous Page</a> | <a href="rbafzmsthselectstmt.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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<a id="Bot_Of_Page" name="Bot_Of_Page"></a>
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</body>
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</html>
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