mysql_ping
(PHP 4 >= 4.3.0, PHP 5, PECL mysql:1.0)
mysql_ping — Ping a server connection or reconnect if there is no connection
說明
bool mysql_ping
([ resource $link_identifier
] )
Checks whether or not the connection to the server is working. If it has gone down, an automatic reconnection is attempted. This function can be used by scripts that remain idle for a long while, to check whether or not the server has closed the connection and reconnect if necessary.
Note: Since MySQL 5.0.13, automatic reconnection feature is disabled.
參數
- link_identifier
-
MySQL 的連接識別符。如果沒有指定，預設使用最後被 mysql_connect() 打開的連接。如果沒有找到該連接，函式會嘗試呼叫 mysql_connect() 建立連接並使用它。如果發生意外，沒有找到連接或無法建立連接，系統發出 E_WARNING 級別的警告信息。
Return值
Returns TRUE if the connection to the server MySQL server is working, otherwise FALSE.
範例
Example#1 A mysql_ping() example
<?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);
?>