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<h1>Db::cursor</h1>
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<h3><pre>
#include <db_cxx.h>
<p>
int
Db::cursor(DbTxn *txnid, Dbc **cursorp, u_int32_t flags);
</pre></h3>
<h1>Description</h1>
<p>The Db::cursor method
creates a cursor and copies a pointer to it into the memory to which
<b>cursorp</b> refers.
<p>If the operation is to be transaction-protected, the <b>txnid</b>
parameter is a transaction handle returned from <a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a>;
otherwise, NULL.
<p>To transaction-protect cursor operations, cursors must be opened and
closed within the context of a transaction, and the <b>txnid</b>
parameter specifies the transaction context in which the cursor may be
used.
<p>The <b>flags</b> value must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one or
more of the following values:
<p><dl compact>
<p><dt><a name="DB_DIRTY_READ">DB_DIRTY_READ</a><dd>All read operations performed by the cursor may return modified but not
yet committed data. Silently ignored if the <a href="../api_cxx/db_open.html#DB_DIRTY_READ">DB_DIRTY_READ</a> flag
was not specified when the underlying database was opened.
<p><dt><a name="DB_WRITECURSOR">DB_WRITECURSOR</a><dd>Specify that the cursor will be used to update the database. The
underlying database environment must have been opened using the
<a href="../api_cxx/env_open.html#DB_INIT_CDB">DB_INIT_CDB</a> flag.
</dl>
<p>The Db::cursor 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.
<h1>Errors</h1>
<p>The Db::cursor method may fail and throw an exception or return a non-zero error for the following conditions:
<p><dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
</dl>
<p>The Db::cursor method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the Db::cursor method may fail and
either return <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a> or throw a
<a href="../api_cxx/runrec_class.html">DbRunRecoveryException</a>,
in which case all subsequent Berkeley DB calls will fail in the same way.
<h1>Class</h1>
<a href="../api_cxx/dbc_class.html">Dbc</a>
<h1>See Also</h1>
<a href="../api_cxx/dbc_list.html">Database Cursors and Related Methods</a>
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