fetchcolumn.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="pdostatement.fetchcolumn" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>PDOStatement::fetchColumn</refname>
  <refpurpose>
   Returns a single column from the next row of a result set
  </refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier> <type>mixed</type><methodname>PDOStatement::fetchColumn</methodname>
   <methodparam choice="opt"><type>int</type><parameter>column_number</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>

  <para>
   Returns a single column from the next row of a result set or &false; if
   there are no more rows.
  </para>

  <note>
   <para>
    <function>PDOStatement::fetchColumn</function> should not be used to
    retrieve boolean columns, as it is impossible to distinguish a value of
    &false; from there being no more rows to retrieve. Use
    <function>PDOStatement::fetch</function> instead.
   </para>
  </note>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>column_number</parameter></term>
     <listitem>
      <para>
       0-indexed number of the column you wish to retrieve from the row. If
       no value is supplied, <function>PDOStatement::fetchColumn</function>
       fetches the first column.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   <function>PDOStatement::fetchColumn</function> returns a single column
   in the next row of a result set.
  </para>
  <warning>
   <para>
    There is no way to return another column from the same row if you
    use <function>PDOStatement::fetchColumn</function> to retrieve data.
   </para>
  </warning>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example><title>Return first column of the next row</title>
    <programlisting role="php">
<![CDATA[
<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();

print("Fetch the first column from the first row in the result set:\n");
$result = $sth->fetchColumn();
print("name = $result\n");

print("Fetch the second column from the second row in the result set:\n");
$result = $sth->fetchColumn(1);
print("colour = $result\n");
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Fetch the first column from the first row in the result set:
name = lemon
Fetch the second column from the second row in the result set:
colour = red
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>PDO::query</function></member>
    <member><function>PDOStatement::fetch</function></member>
    <member><function>PDOStatement::fetchAll</function></member>
    <member><function>PDO::prepare</function></member>
    <member><function>PDOStatement::setFetchMode</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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