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, "-- ---------------------------------------------------------\n");

            fwrite($file, "-- Database Name: $db\n");

            fwrite($file, "-- ---------------------------------------------------------\n\n");

            fwrite($file, "/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;\n");

            fwrite($file, "/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;\n");

            fwrite($file, "/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;\n");

            fwrite($file, "/*!40101 SET NAMES '".mysql_client_encoding()."' */;\n");

            fwrite($file, "/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;\n");

            fwrite($file, "/*!40103 SET TIME_ZONE='".mysql_result(mysql_query("SELECT @@time_zone"),0)."' */;\n");

            fwrite($file, "/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;\n");

            fwrite($file, "/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;\n");

            fwrite($file, "/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;\n");

            fwrite($file, "/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;\n\n");

            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, "\n");

            fwrite($file, "/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;\n");

            fwrite($file, "/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;\n");

            fwrite($file, "/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;\n");

            fwrite($file, "/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;\n");

            fwrite($file, "/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;\n");

            fwrite($file, "/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;\n");

            fwrite($file, "/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;\n");

            fwrite($file, "/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;\n");

            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, "\n");

    fwrite($file, "--\n");

    fwrite($file, "-- Table structure for table $table\n");

    fwrite($file, "--\n\n");

    fwrite($file, "DROP TABLE IF EXISTS `" . $table .  "`;\n");

    fwrite($file, "/*!40101 SET @saved_cs_client     = @@character_set_client */;\n");

    fwrite($file, "/*!40101 SET character_set_client = '".mysql_client_encoding()."' */;\n");

    $result=mysql_query("SHOW CREATE TABLE `".$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'].";\n");

    fwrite($file, "/*!40101 SET character_set_client = @saved_cs_client */;\n");

    $result=mysql_query("SELECT * FROM `".$table."`");

    if (!$result) {

        echo sprintf('Database error %1$s for query %2$s', mysql_error(), "SELECT * FROM `".$table."`")."<br/>";

        return false;

    }

    fwrite($file, "--\n");

    fwrite($file, "-- Dumping data for table $table\n");

    fwrite($file, "--\n\n");

    if ($status['Engine']=='MyISAM')

        fwrite($file, "/*!40000 ALTER TABLE `".$table."` DISABLE KEYS */;\n");

    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)." );\n");

    }

    if ($status['Engine']=='MyISAM')

        fwrite($file, "/*!40000 ALTER TABLE ".$table." ENABLE KEYS */;\n");

}

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');