php-doc-en/reference/mysqli/functions/mysqli-change-user.xml

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<!-- $Revision: 1.17 $ -->
<refentry xml:id="function.mysqli-change-user" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysqli_change_user</refname>
  <refname>mysqli->change_user()</refname>
  <refpurpose>Changes the user of the specified database connection</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>Procedural style:</para>
  <methodsynopsis>
   <type>bool</type><methodname>mysqli_change_user</methodname>
   <methodparam><type>mysqli</type><parameter>link</parameter></methodparam>
   <methodparam><type>string</type><parameter>user</parameter></methodparam>
   <methodparam><type>string</type><parameter>password</parameter></methodparam>
   <methodparam><type>string</type><parameter>database</parameter></methodparam>
  </methodsynopsis>
  <para>Object oriented style (method):</para>
  <classsynopsis>
   <ooclass><classname>mysqli</classname></ooclass>
   <methodsynopsis>
    <type>bool</type><methodname>change_user</methodname>
    <methodparam><type>string</type><parameter>user</parameter></methodparam>
    <methodparam><type>string</type><parameter>password</parameter></methodparam>
    <methodparam><type>string</type><parameter>database</parameter></methodparam>
   </methodsynopsis>
  </classsynopsis>
  <para>
   Changes the user of the specified database connection and sets the current
   database.
  </para>
  <para>
   In order to successfully change users a valid <parameter>username</parameter> and
   <parameter>password</parameter> parameters must be provided and that user must have
   sufficient permissions to access the desired database. If for any reason authorization
   fails, the current user authentication will remain.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &mysqli.link.description;
    <varlistentry>
     <term><parameter>user</parameter></term>
     <listitem>
      <para>
       The MySQL user name.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>password</parameter></term>
     <listitem>
      <para>
       The MySQL password.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>database</parameter></term>
     <listitem>
      <para>
       The database to change to.
      </para>
      <para>
       If desired, the &null; value may be passed resulting in only changing
       the user and not selecting a database. To select a database in this
       case use the <function>mysqli_select_db</function> function.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

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

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    Using this command will always cause the current database connection to
    behave as if was a completely new database connection, regardless of if
    the operation was completed successfully. This reset includes performing
    a rollback on any active transactions, closing all temporary tables, and
    unlocking all locked tables.
   </para>
  </note>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
   <example>
    <title>Object oriented style</title>
    <programlisting role="php">
<![CDATA[
<?php

/* connect database test */
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");

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

/* Set Variable a */
$mysqli->query("SET @a:=1");

/* reset all and select a new database */
$mysqli->change_user("my_user", "my_password", "world");

if ($result = $mysqli->query("SELECT DATABASE()")) {
    $row = $result->fetch_row();
    printf("Default database: %s\n", $row[0]);
    $result->close();
}

if ($result = $mysqli->query("SELECT @a")) {
    $row = $result->fetch_row();
    if ($row[0] === NULL) {
        printf("Value of variable a is NULL\n");
    }
    $result->close();
}

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

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

/* Set Variable a */
mysqli_query($link, "SET @a:=1");

/* reset all and select a new database */
mysqli_change_user($link, "my_user", "my_password", "world");

if ($result = mysqli_query($link, "SELECT DATABASE()")) {
    $row = mysqli_fetch_row($result);
    printf("Default database: %s\n", $row[0]);
    mysqli_free_result($result);
}

if ($result = mysqli_query($link, "SELECT @a")) {
    $row = mysqli_fetch_row($result);
    if ($row[0] === NULL) {
        printf("Value of variable a is NULL\n");
    }
    mysqli_free_result($result);
}

/* close connection */
mysqli_close($link);
?>
]]>
   </programlisting>
  </example>
  &example.outputs;
  <screen>
<![CDATA[
Default database: world
Value of variable a is NULL
]]>
  </screen>
 </refsect1>

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

</refentry>

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