PHP导出数据库方法

（1）定义一个db_dump函数如下：
<?PHP
function db_dump($host,$user,$pwd,$db) {
    $mysqlconlink = mysql_connect($host,$user,$pwd , true);
    if (!$mysqlconlink)
        echo sprintf('No MySQL connection: %s',mysql_error())."<br/>";
    mysql_set_charset( 'utf8', $mysqlconlink );
    $mysqldblink = mysql_select_db($db,$mysqlconlink);
    if (!$mysqldblink)
        echo sprintf('No MySQL connection to database: %s',mysql_error())."<br/>";
    $tabelstobackup=array();
    $result=mysql_query("SHOW TABLES FROM `$db`");
    if (!$result)
        echo sprintf('Database error %1$s for query %2$s', mysql_error(), "SHOW TABLE STATUS FROM `$db`;")."<br/>";
    while ($data = mysql_fetch_row($result)) {
            $tabelstobackup[]=$data[0];
    }
    if (count($tabelstobackup)>0) {
        $result=mysql_query("SHOW TABLE STATUS FROM `$db`");
        if (!$result)
            echo sprintf('Database error %1$s for query %2$s', mysql_error(), "SHOW TABLE STATUS FROM `$db`;")."<br/>";
        while ($data = mysql_fetch_assoc($result)) {
            $status[$data['Name']]=$data;
        }
        if ($file = fopen("$db.sql", 'wb')) {
            fwrite($file, "-- ---------------------------------------------------------
");
            fwrite($file, "-- Database Name: $db
");
            fwrite($file, "-- ---------------------------------------------------------

");
            fwrite($file, "/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
");
            fwrite($file, "/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
");
            fwrite($file, "/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
");
            fwrite($file, "/*!40101 SET NAMES '".mysql_client_encoding()."' */;
");
            fwrite($file, "/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
");
            fwrite($file, "/*!40103 SET TIME_ZONE='".mysql_result(mysql_query("SELECT @@time_zone"),0)."' */;
");
            fwrite($file, "/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
");
            fwrite($file, "/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
");
            fwrite($file, "/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
");
            fwrite($file, "/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;

");
            foreach($tabelstobackup as $table) {
                echo sprintf('Dump database table "%s"',$table)."<br/>";
                need_free_memory(($status[$table]['Data_length']+$status[$table]['Index_length'])*3);
                _db_dump_table($table,$status[$table],$file);
            }
            fwrite($file, "
");
            fwrite($file, "/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
");
            fwrite($file, "/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
");
            fwrite($file, "/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
");
            fwrite($file, "/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
");
            fwrite($file, "/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
");
            fwrite($file, "/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
");
            fwrite($file, "/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
");
            fwrite($file, "/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
");
            fclose($file);
            echo 'Database dump done!'."<br/>";
        } else {
            echo 'Can not create database dump!'."<br/>";
        }
    } else {
        echo 'No tables to dump'."<br/>";
    }
}
function _db_dump_table($table,$status,$file) {
    fwrite($file, "
");
    fwrite($file, "--
");
    fwrite($file, "-- Table structure for table $table
");
    fwrite($file, "--

");
    fwrite($file, "DROP TABLE IF EXISTS `" . $table .  "`;
");
    fwrite($file, "/*!40101 SET @saved_cs_client     = @@character_set_client */;
");
    fwrite($file, "/*!40101 SET character_set_client = '".mysql_client_encoding()."' */;
");
    $result=mysql_query("SHOW CREATE TABLE `".$table."`");
    if (!$result) {
        echo sprintf('Database error %1$s for query %2$s', mysql_error(), "SHOW CREATE TABLE `".$table."`")."<br/>";
        return false;
    }
    $tablestruc=mysql_fetch_assoc($result);
    fwrite($file, $tablestruc['Create Table'].";
");
    fwrite($file, "/*!40101 SET character_set_client = @saved_cs_client */;
");
    $result=mysql_query("SELECT * FROM `".$table."`");
    if (!$result) {
        echo sprintf('Database error %1$s for query %2$s', mysql_error(), "SELECT * FROM `".$table."`")."<br/>";
        return false;
    }
    fwrite($file, "--
");
    fwrite($file, "-- Dumping data for table $table
");
    fwrite($file, "--

");
    if ($status['Engine']=='MyISAM')
        fwrite($file, "/*!40000 ALTER TABLE `".$table."` DISABLE KEYS */;
");
    while ($data = mysql_fetch_assoc($result)) {
        $keys = array();
        $values = array();
        foreach($data as $key => $value) {
            if($value === NULL)
                $value = "NULL";
            elseif($value === "" or $value === false)
                $value = "''";
            elseif(!is_numeric($value))
                $value = "'".mysql_real_escape_string($value)."'";
            $values[] = $value;
        }
        fwrite($file, "INSERT INTO `".$table."` VALUES ( ".implode(", ",$values)." );
");
    }
    if ($status['Engine']=='MyISAM')
        fwrite($file, "/*!40000 ALTER TABLE ".$table." ENABLE KEYS */;
");
}
function need_free_memory($memneed) {
    if (!function_exists('memory_get_usage'))
        return;
    $needmemory=@memory_get_usage(true)+inbytes($memneed);
    if ($needmemory>inbytes(ini_get('memory_limit'))) {
        $newmemory=round($needmemory/1024/1024)+1 .'M';
        if ($needmemory>=1073741824)
            $newmemory=round($needmemory/1024/1024/1024) .'G';
        if ($oldmem=@ini_set('memory_limit', $newmemory))
            echo sprintf(__('Memory increased from %1$s to %2$s','backwpup'),$oldmem,@ini_get('memory_limit'))."<br/>";
        else
            echo sprintf(__('Can not increase memory limit is %1$s','backwpup'),@ini_get('memory_limit'))."<br/>";
    }
}
function inbytes($value) {
    $multi=strtoupper(substr(trim($value),-1));
    $bytes=abs(intval(trim($value)));
    if ($multi=='G')
        $bytes=$bytes*1024*1024*1024;
    if ($multi=='M')
        $bytes=$bytes*1024*1024;
    if ($multi=='K')
        $bytes=$bytes*1024;
    return $bytes;
}
?>

（2）使用方法：

db_dump('数据库服务器', '数据库用户名', '数据库密码', '数据库名');