<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>DbSequence::open()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="seq.html" title="Chapter 12. The DbSequence Handle" /> <link rel="prev" href="seqinitial_value.html" title="DbSequence::initial_value()" /> <link rel="next" href="seqremove.html" title="DbSequence::remove()" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DbSequence::open()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="seqinitial_value.html">Prev</a> </td> <th width="60%" align="center">Chapter 12. The DbSequence Handle </th> <td width="20%" align="right"> <a accesskey="n" href="seqremove.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="seqopen"></a>DbSequence::open()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int DbSequence::open(DbTxn *txnid, Dbt *key, u_int32_t flags); </pre> <p> The <code class="methodname">DbSequence::open()</code> method opens the sequence represented by the <span class="bold"><strong>key</strong></span>. The key must be compatible with the underlying database specified in the corresponding call to <a class="xref" href="seqcreate.html" title="DbSequence">DbSequence</a>. </p> <p> The <code class="methodname">DbSequence::open()</code> <span> <span> method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1710321"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1710403"></a>key</h4> </div> </div> </div> <p> The <span class="bold"><strong>key</strong></span> specifies which record in the database stores the persistent sequence data. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1710379"></a>flags</h4> </div> </div> </div> <p> The <span class="bold"><strong>flags</strong></span> parameter must be set to 0 or by bitwise inclusively <span class="bold"><strong>OR</strong></span>'ing together one or more of the following values: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">DB_CREATE</code> </p> <p> Create the sequence. If the sequence does not already exist and the <code class="literal">DB_CREATE</code> flag is not specified, the <code class="methodname">DbSequence::open()</code> method will fail. </p> </li> <li> <p> <code class="literal">DB_EXCL</code> </p> <p> Return an error if the sequence already exists. This flag is only meaningful when specified with the <code class="literal">DB_CREATE</code> flag. </p> </li> <li> <p><a id="seqopen_DB_THREAD"></a> <code class="literal">DB_THREAD</code> </p> <p> Cause the <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a> handle returned by <code class="methodname">DbSequence::open()</code> to be <span class="emphasis"><em>free-threaded</em></span>; that is, usable by multiple threads within a single address space. Note that if multiple threads create multiple sequences using the same database handle that handle must have been opened specifying this flag. </p> </li> </ul> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1710820"></a>txnid</h4> </div> </div> </div> <p> If the operation is part of an application-specified transaction, the <span class="bold"><strong>txnid</strong></span> parameter is a transaction handle returned from <a class="xref" href="txnbegin.html" title="DbEnv::txn_begin()">DbEnv::txn_begin()</a>; if the operation is part of a Berkeley DB Concurrent Data Store group, the <span class="bold"><strong>txnid</strong></span> parameter is a handle returned from <a class="xref" href="envcdsgroup_begin.html" title="DbEnv::cdsgroup_begin()">DbEnv::cdsgroup_begin()</a>; otherwise NULL. If no transaction handle is specified, but the operation occurs in a transactional database, the operation will be implicitly transaction protected. Transactionally protected operations on a <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a> handle require the <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a> handle itself be transactionally protected during its open if the open creates the sequence. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1710782"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1710833"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="seq.html#seqlist" title="Sequences and Related Methods">Sequences and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="seqinitial_value.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="seq.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="seqremove.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbSequence::initial_value() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbSequence::remove()</td> </tr> </table> </div> </body> </html>