libdb/docs/api_reference/TCL/db_join.html
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<th colspan="3" align="center"><span xmlns="http://www.w3.org/1999/xhtml" class="emphasis"><em>db</em></span> join</th>
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<h2 class="title" style="clear: both"><a id="db_join"></a><span class="emphasis"><em>db</em></span> join</h2>
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<pre class="programlisting">db join
<span class="emphasis"><em>db.cX</em></span>
<span class="emphasis"><em>db.cY</em></span>
<span class="emphasis"><em>db.cZ</em></span>
... </pre>
<p>
The <span class="emphasis"><em>db</em></span> <span class="bold"><strong>join</strong></span>
command joins the specified cursors and returns a cursor handle that
can be used to iterate through the joined {key data} pairs. The
returned cursor handle is bound to a Tcl command of the form <span class="bold"><strong>dbN.cX</strong></span>, where X is an integer starting at 0
(for example, db0.c0 and db0.c1). It is through this Tcl command that
the script accesses the cursor methods.
</p>
<p>
The returned join cursor has limited cursor functionality, and only
the <span class="emphasis"><em>dbc</em></span> <span class="bold"><strong>get</strong></span> and
<span class="emphasis"><em>dbc</em></span> <span class="bold"><strong>close</strong></span>
commands will succeed.
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<p>
See <a href="../../programmer_reference/am_cursor.html#am_join" class="olink">Equality Join</a>
in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em> for more
information on the underlying requirements for joining.
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In a transaction-protected environment, all the cursors listed must
have been created within the same transaction.
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In the case of error, a Tcl error is thrown.
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