mysql-ping.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- EN-Revision: ed56c4e375ef51f88d578741f1b5074d31fc0988 Maintainer: dallas Status: ready -->
<!-- CREDITS: mowangjuanzi -->
<refentry xml:id="function.mysql-ping" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysql_ping</refname>
  <refpurpose>Ping 服务器连接的状态，如果没有连接则重新连接</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
  <warning>
   &mysql.alternative.note;
   <simplelist role="alternatives">
    <member><function>mysqli_ping</function></member>
   </simplelist>
  </warning>
 </refsynopsisdiv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>mysql_ping</methodname>
   <methodparam choice="opt"><type>resource</type><parameter>link_identifier</parameter><initializer>NULL</initializer></methodparam>
  </methodsynopsis>
  <para>
   检查到服务器的连接是否正常。如果断开，则自动尝试连接。本函数可用于空闲很久的脚本来检查服务器是否关闭了连接，如果有必要则重新连接上。。
  </para>
  <note>
   <para>
    从 MySQL 版本 5.0.3 开始，默认情况下不启用自动重新连接功能。
   </para>
  </note>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &mysql.linkid.description;
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   如果到服务器的连接可用则，返回 &true;，否则返回 &false;。
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>mysql_ping</function> 示例</title>
    <programlisting role="php">
<![CDATA[
<?php
set_time_limit(0);

$conn = mysql_connect('localhost', 'mysqluser', 'mypass');
$db   = mysql_select_db('mydb');

/* Assuming this query will take a long time */
$result = mysql_query($sql);
if (!$result) {
    echo 'Query #1 failed, exiting.';
    exit;
}

/* Make sure the connection is still alive, if not, try to reconnect */
if (!mysql_ping($conn)) {
    echo 'Lost connection, exiting after query #1';
    exit;
}
mysql_free_result($result);

/* So the connection is still alive, let's run another query */
$result2 = mysql_query($sql2);
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

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

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