php如何设置表前缀

<?php
 $database = "databaseName"; //数据库名称
 $user = "root"; //数据库用户名
 $pwd = "pwd"; //数据库密码
 $replace ='pre_'; //替换后的前缀
 $seach = 'pre1_'; //要替换的前缀
 $db=mysql_connect("localhost","$user","$pwd") or die("连接数据库失败：".mysql_error()); //连接数据库
 
 $tables = mysql_list_tables("$database"); 
 while($name = mysql_fetch_array($tables)) {
 
 $table = str_replace($seach,$replace,$name['0']);
 
 mysql_query("rename table $name[0] to $table");
 }
 
?>

$table = str_replace($seach,$replace,$name['0']);换成
 $table = $replace.$name['0'];