php-doc-en/reference/mysqli/functions/mysqli-prepare.xml

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<refentry id="function.mysqli-prepare">
 <refnamediv>
  <refname>mysqli_prepare</refname>
  <refname>mysqli->prepare()</refname>
  <refpurpose>Prepare a SQL statement for execution</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>Procedure style:</para>
  <methodsynopsis>
   <type>mysqli_stmt</type><methodname>mysqli_prepare</methodname>
   <methodparam><type>mysqli</type><parameter>link</parameter></methodparam>
   <methodparam><type>string</type><parameter>query</parameter></methodparam>
  </methodsynopsis>
  <para>Object oriented style (method)</para>
  <classsynopsis>
   <ooclass><classname>mysqli</classname></ooclass>
   <methodsynopsis>
    <type>mysqli_stmt</type><methodname>prepare</methodname>
    <methodparam><type>string</type><parameter>query</parameter></methodparam>
   </methodsynopsis>
  </classsynopsis>
  <para>
   Prepares the SQL query pointed to by the null-terminated string query, and
   returns a statement handle to be used for further operations on the
   statement. The query must consist of a single SQL statement.
  </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>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &mysqli.link.description;
    <varlistentry>
     <term><parameter>query</parameter></term>
     <listitem>
      <para>
       The query, as a string.
      </para>
      <note>
       <para>
        You should not add a terminating semicolon or <literal>\g</literal>
        to the statement.
       </para>
      </note>
      <para>
       This parameter 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>
        The markers are legal only in certain places in SQL statements.
        For example, they are allowed in the <literal>VALUES()</literal>
        list of an <literal>INSERT</literal> statement (to specify column
        values for a row), or in a comparison with a column in a
        <literal>WHERE</literal> 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 <literal>SELECT</literal> 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. It's not allowed to
        compare marker with <literal>NULL</literal> by 
        <literal>? IS NULL</literal> too. In general, parameters are legal
        only in Data Manipulation Languange (DML) statements, and not in Data
        Defination Language (DDL) statements.
       </para>
      </note>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   <function>mysqli_prepare</function> returns a statement object or &false; if an error occured.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title>Object oriented style</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 */
if ($stmt = $mysqli->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>Procedural style</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 */
if ($stmt = mysqli_prepare($link, "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>
  </example>
  &example.outputs;
  <screen>
<![CDATA[
Amersfoort is in district Utrecht
]]>
  </screen>
 </refsect1>

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

</refentry>

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