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202 lines
8.6 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DbSequence::open()</title>
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<link rel="stylesheet" href="apiReference.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB C++ API Reference" />
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<link rel="up" href="seq.html" title="Chapter 12. The DbSequence Handle" />
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<link rel="prev" href="seqinitial_value.html" title="DbSequence::initial_value()" />
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<link rel="next" href="seqremove.html" title="DbSequence::remove()" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DbSequence::open()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="seqinitial_value.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 12.
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The DbSequence Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="seqremove.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="seqopen"></a>DbSequence::open()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db_cxx.h>
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int
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DbSequence::open(DbTxn *txnid, Dbt *key, u_int32_t flags); </pre>
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<p>
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The <code class="methodname">DbSequence::open()</code> method opens the sequence represented by the
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<span class="bold"><strong>key</strong></span>. The key must be compatible with
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the underlying database specified in the corresponding call to
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<a class="xref" href="seqcreate.html" title="DbSequence">DbSequence</a>.
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</p>
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<p>
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The <code class="methodname">DbSequence::open()</code> <span>
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<span>
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method either returns a non-zero error value or throws an
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exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</span>
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</span>
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</p>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3649147"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3649136"></a>key</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>key</strong></span> specifies which record in the
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database stores the persistent sequence data.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3648724"></a>flags</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
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or by bitwise inclusively <span class="bold"><strong>OR</strong></span>'ing
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together one or more of the following values:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<code class="literal">DB_CREATE</code>
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</p>
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<p>
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Create the sequence. If the sequence does not already exist and the
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<code class="literal">DB_CREATE</code> flag is not specified, the
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<code class="methodname">DbSequence::open()</code> method will fail.
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</p>
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</li>
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<li>
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<p>
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<code class="literal">DB_EXCL</code>
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</p>
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<p>
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Return an error if the sequence already exists. This flag is only
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meaningful when specified with the <code class="literal">DB_CREATE</code> flag.
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</p>
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</li>
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<li>
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<p><a id="seqopen_DB_THREAD"></a>
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<code class="literal">DB_THREAD</code>
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</p>
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<p>
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Cause the <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a>
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handle returned by <code class="methodname">DbSequence::open()</code> to be
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<span class="emphasis"><em>free-threaded</em></span>; that is, usable by multiple
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threads within a single address space. Note that if multiple threads
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create multiple sequences using the same database handle that handle
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must have been opened specifying this flag.
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</p>
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</li>
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</ul>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3649231"></a>txnid</h4>
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</div>
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</div>
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</div>
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<p>
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If the operation is part of an application-specified transaction, the
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<span class="bold"><strong>txnid</strong></span> parameter is a transaction
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handle returned from <a class="xref" href="txnbegin.html" title="DbEnv::txn_begin()">DbEnv::txn_begin()</a>; if the
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operation is part of a Berkeley DB Concurrent Data Store group, the
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<span class="bold"><strong>txnid</strong></span> parameter is a handle returned
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from <a class="xref" href="envcdsgroup_begin.html" title="DbEnv::cdsgroup_begin()">DbEnv::cdsgroup_begin()</a>;
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otherwise NULL. If no transaction handle is specified, but the
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operation occurs in a transactional database, the operation will be
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implicitly transaction protected. Transactionally protected operations
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on a <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a> handle
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require the <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a>
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handle itself be transactionally protected during its open if the open
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creates the sequence.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3648938"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a>
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3649161"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="seq.html#seqlist" title="Sequences and Related Methods">Sequences and Related Methods</a>
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="seqinitial_value.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="seq.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="seqremove.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DbSequence::initial_value() </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> DbSequence::remove()</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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