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<refentry xml:id="mysqli-stmt.prepare" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysqli_stmt::prepare</refname>
  <refname>mysqli_stmt_prepare</refname>
  <refpurpose>Prepare an SQL statement for execution</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>&style.oop;</para>
  <methodsynopsis role="oop">
   <type>mixed</type><methodname>mysqli_stmt::prepare</methodname>
   <methodparam><type>string</type><parameter>query</parameter></methodparam>
  </methodsynopsis>
  <para>&style.procedural;</para>
  <methodsynopsis>
   <type>bool</type><methodname>mysqli_stmt_prepare</methodname>
   <methodparam><type>mysqli_stmt</type><parameter>stmt</parameter></methodparam>
   <methodparam><type>string</type><parameter>query</parameter></methodparam>
  </methodsynopsis>
  <para>
   Prepares the SQL query pointed to by the null-terminated string query. 
  </para>
  <para>
   The parameter markers must be bound to application variables using
   <function>mysqli_stmt_bind_param</function> and/or 
   <function>mysqli_stmt_bind_result</function> before executing the
   statement or fetching rows.
  </para>
  <note>
   <para>
    In the case where you pass a statement to
    <function>mysqli_stmt_prepare</function> that is longer than
    <literal>max_allowed_packet</literal> of the server, the returned
    error codes are different depending on whether you are using MySQL
    Native Driver (<literal>mysqlnd</literal>) or MySQL Client Library
    (<literal>libmysqlclient</literal>). The behavior is as follows:
   </para>
   <itemizedlist>
    <listitem>
     <para>
      <literal>mysqlnd</literal> on Linux returns an error code of 1153.
      The error message means <quote>got a packet bigger than
      <literal>max_allowed_packet</literal> bytes</quote>.
     </para>
    </listitem>
    <listitem>
     <para>
      <literal>mysqlnd</literal> on Windows returns an error code 2006.
      This error message means <quote>server has gone away</quote>.
     </para>
    </listitem>
    <listitem>
     <para>
      <literal>libmysqlclient</literal> on all platforms returns an error code
      2006. This error message means <quote>server has gone
      away</quote>.
     </para>
    </listitem>
   </itemizedlist>
  </note>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &mysqli.stmt.description;
    <varlistentry>
     <term><parameter>query</parameter></term>
     <listitem>
      <para>
       The query, as a string. It must consist of a single SQL statement.
      </para>
      <para>
       You can include one or more parameter markers in the SQL statement by
       embedding question mark (<literal>?</literal>) characters at the
       appropriate positions.
      </para>
      <note>
       <para>
        You should not add a terminating semicolon or <literal>\g</literal>
        to the statement.
       </para>
      </note>
      <note>
       <para>
        The markers are legal only in certain places in SQL statements.
        For example, they are allowed in the VALUES() list of an INSERT statement
        (to specify column values for a row), or in a comparison with a column in
        a WHERE clause to specify a comparison value.
       </para>
       <para>
        However, they are not allowed for identifiers (such as table or column names),
        in the select list that names the columns to be returned by a SELECT statement),
        or to specify both operands of a binary operator such as the <literal>=</literal>
        equal sign. The latter restriction is necessary because it would be impossible
        to determine the parameter type. In general, parameters are legal only in Data
        Manipulation Language (DML) statements, and not in Data Definition Language
        (DDL) statements.
       </para>
      </note>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </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", "world");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

$city = "Amersfoort";

/* create a prepared statement */
$stmt =  $mysqli->stmt_init();
if ($stmt->prepare("SELECT District FROM City WHERE Name=?")) {

    /* bind parameters for markers */
    $stmt->bind_param("s", $city);

    /* execute query */
    $stmt->execute();

    /* bind result variables */
    $stmt->bind_result($district);

    /* fetch value */
    $stmt->fetch();

    printf("%s is in district %s\n", $city, $district);

    /* close statement */
    $stmt->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", "world");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

$city = "Amersfoort";

/* create a prepared statement */
$stmt = mysqli_stmt_init($link);
if (mysqli_stmt_prepare($stmt, 'SELECT District FROM City WHERE Name=?')) {

    /* bind parameters for markers */
    mysqli_stmt_bind_param($stmt, "s", $city);

    /* execute query */
    mysqli_stmt_execute($stmt);

    /* bind result variables */
    mysqli_stmt_bind_result($stmt, $district);

    /* fetch value */
    mysqli_stmt_fetch($stmt);

    printf("%s is in district %s\n", $city, $district);

    /* close statement */
    mysqli_stmt_close($stmt);
}

/* close connection */
mysqli_close($link);
?>
]]>
   </programlisting>
   &examples.outputs;
   <screen>
<![CDATA[
Amersfoort is in district Utrecht
]]>
   </screen>
  </example>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>mysqli_stmt_init</function></member>
    <member><function>mysqli_stmt_execute</function></member>
    <member><function>mysqli_stmt_fetch</function></member>
    <member><function>mysqli_stmt_bind_param</function></member>
    <member><function>mysqli_stmt_bind_result</function></member>
    <member><function>mysqli_stmt_get_result</function></member>
    <member><function>mysqli_stmt_close</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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