result-metadata.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="mysqli-stmt.result-metadata" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysqli_stmt::result_metadata</refname>
  <refname>mysqli_stmt_result_metadata</refname>
  <refpurpose>Returns result set metadata from a prepared statement</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>&style.oop;</para>
  <methodsynopsis role="oop">
   <type>mysqli_result</type><methodname>mysqli_stmt::result_metadata</methodname>
   <void />
  </methodsynopsis>
  <para>&style.procedural;</para>
  <methodsynopsis>
   <type>mysqli_result</type><methodname>mysqli_stmt_result_metadata</methodname>
   <methodparam><type>mysqli_stmt</type><parameter>stmt</parameter></methodparam>
  </methodsynopsis>
  <para>
   If a statement passed to <function>mysqli_prepare</function> is one that produces
   a result set, <function>mysqli_stmt_result_metadata</function> returns the result object
   that can be used to process the meta information such as total number of fields
   and individual field information.
  </para>
  <note>
   <para>This result set pointer can be passed as an argument to any of the
    field-based functions that process result set metadata, such as:
    <itemizedlist>
     <listitem><para><function>mysqli_num_fields</function></para></listitem>
     <listitem><para><function>mysqli_fetch_field</function></para></listitem>
     <listitem><para><function>mysqli_fetch_field_direct</function></para></listitem>
     <listitem><para><function>mysqli_fetch_fields</function></para></listitem>
     <listitem><para><function>mysqli_field_count</function></para></listitem>
     <listitem><para><function>mysqli_field_seek</function></para></listitem>
     <listitem><para><function>mysqli_field_tell</function></para></listitem>
     <listitem><para><function>mysqli_free_result</function></para></listitem>
    </itemizedlist>
   </para>
  </note>
  <para>
   The result set structure should be freed when you are done with it,
   which you can do by passing it to <function>mysqli_free_result</function>
  </para>
  <note>
   <para>
    The result set returned by <function>mysqli_stmt_result_metadata</function> contains only
    metadata. It does not contain any row results. The rows are obtained by using the
    statement handle with <function>mysqli_stmt_fetch</function>.
   </para>
  </note>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &mysqli.stmt.description;
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a result object or &false; if an error occurred.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title>&style.oop;</title>
   <programlisting role="php">
<![CDATA[
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");

$mysqli->query("DROP TABLE IF EXISTS friends");
$mysqli->query("CREATE TABLE friends (id int, name varchar(20))");

$mysqli->query("INSERT INTO friends VALUES (1,'Hartmut'), (2, 'Ulf')");

$stmt = $mysqli->prepare("SELECT id, name FROM friends");
$stmt->execute();

/* get resultset for metadata */
$result = $stmt->result_metadata();

/* retrieve field information from metadata result set */
$field = $result->fetch_field();

printf("Fieldname: %s\n", $field->name);

/* close resultset */
$result->close();

/* close connection */
$mysqli->close();
?>
]]>
   </programlisting>
  </example>
  <example>
   <title>&style.procedural;</title>
   <programlisting role="php">
<![CDATA[
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "test");

mysqli_query($link, "DROP TABLE IF EXISTS friends");
mysqli_query($link, "CREATE TABLE friends (id int, name varchar(20))");

mysqli_query($link, "INSERT INTO friends VALUES (1,'Hartmut'), (2, 'Ulf')");

$stmt = mysqli_prepare($link, "SELECT id, name FROM friends");
mysqli_stmt_execute($stmt);

/* get resultset for metadata */
$result = mysqli_stmt_result_metadata($stmt);

/* retrieve field information from metadata result set */
$field = mysqli_fetch_field($result);

printf("Fieldname: %s\n", $field->name);

/* close resultset */
mysqli_free_result($result);

/* close connection */
mysqli_close($link);
?>
]]>
   </programlisting>
  </example>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>mysqli_prepare</function></member>
    <member><function>mysqli_free_result</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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