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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
-
- This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
- project.
-
- Copyright (C) 1998-2018 OpenLink Software
-
- This project is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by the
- Free Software Foundation; only version 2 of the License, dated June 1991.
-
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-
-
-->
<refentry id="xpf_distinct">
<refmeta>
<refentrytitle>distinct</refentrytitle>
<refmiscinfo>XPATH</refmiscinfo>
</refmeta>
<refnamediv>
<refname>distinct</refname>
<refpurpose>Removes double entities from the input sequence </refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="xpf_syn_distinct">
<funcprototype id="xpf_proto_distinct">
<funcdef>sequence <function>distinct</function></funcdef>
<paramdef><parameter>input</parameter> sequence</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="xpf_desc_distinct"><title>Description</title>
<para>The function takes a single parameter which is sequence of XML entities (nodes or values) and
returns the sequence that results from removing from input sequence all but one of a set of elements
that are identical each other. If input sequence is the empty, the empty sequence is returned.
</para>
<para>
Note that the <function>distinct</function> is not a part of XPATH 1.0
or XQuery 1.0 standard library, it is rather a generalization of standard <function>distinct-nodes</function> and
<function>distinct-values</function> functions.
</para>
</refsect1>
<refsect1 id="xpf_params_distinct"><title>Parameters</title>
<refsect2><title>input</title>
<para>The sequence of XML entities </para></refsect2>
</refsect1>
<refsect1 id="xpf_ret_distinct"><title>Return Types</title><para>Sequence</para></refsect1>
<refsect1 id="xpf_examples_distinct"><title>Examples</title>
<example id="xpf_ex_distinct"><title>Removing double entities</title>
<para>In the following example the file example.xml is </para>
<screen>
<a>
<b/>
<b/>
</a>
</screen>
<para>
The result of the query
</para>
<screen>
<result>
{
distinct(for $r in document("example.xml")//b return $r)
}
</result>
</screen>
<para>
is only one 'b' element:
</para>
<screen>
<result>
<b/>
</result>
</screen>
</example>
</refsect1>
</refentry>
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