使用php代码备份SQL数据库，但会保存空白SQL文件

这是我备份数据库的代码，它现在可以工作了，但我只能得到一个空的SQL文件，。有人能帮我吗？我要用什么，mysqlidump还是mysqldump

<?php
$cookie_name = "abc";
$cookie_value = "nk";
setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); // 86400 = 1 day

define("BACKUP_PATH","C:/wamp64/www/db/dbbackup/");

$dump_path = "db/dbbackup/";
$dbhost = "localhost";
$username = "root";
$password = "";
$dbname = "trust";
$date_string = date('Ymd');
$user_id = $_COOKIE["abc"];
$command = "mysqldump --routines -h {$dbhost} -u {$username} {$dbname} >". BACKUP_PATH ."{$date_string}_{$dbname}.sql";
system($command);

echo "<script> alert('backup saved'); window.location.href='setting.php?id=".$user_id."' </script>";?>

试试这段代码

只需添加您的
数据库名称、主机、密码等

语法

EXPORT_TABLES("localhost","user","pass","db_name" );

代码：

<?php

function EXPORT_TABLES($host,$user,$pass,$name,$tables=false, $backup_name=false){ 
    set_time_limit(3000); $mysqli = new mysqli($host,$user,$pass,$name); $mysqli->select_db($name); $mysqli->query("SET NAMES 'utf8'");
    $queryTables = $mysqli->query('SHOW TABLES'); while($row = $queryTables->fetch_row()) { $target_tables[] = $row[0]; }   if($tables !== false) { $target_tables = array_intersect( $target_tables, $tables); } 
    $content = "SET SQL_MODE = \"NO_AUTO_VALUE_ON_ZERO\";\r\nSET time_zone = \"+00:00\";\r\n\r\n\r\n/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;\r\n/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;\r\n/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;\r\n/*!40101 SET NAMES utf8 */;\r\n--\r\n-- Database: `".$name."`\r\n--\r\n\r\n\r\n";
    foreach($target_tables as $table){
        if (empty($table)){ continue; } 
        $result = $mysqli->query('SELECT * FROM `'.$table.'`');     $fields_amount=$result->field_count;  $rows_num=$mysqli->affected_rows;     $res = $mysqli->query('SHOW CREATE TABLE '.$table); $TableMLine=$res->fetch_row(); 
        $content .= "\n\n".$TableMLine[1].";\n\n";
        for ($i = 0, $st_counter = 0; $i < $fields_amount;   $i++, $st_counter=0) {
            while($row = $result->fetch_row())  { //when started (and every after 100 command cycle):
                if ($st_counter%100 == 0 || $st_counter == 0 )  {$content .= "\nINSERT INTO ".$table." VALUES";}
                    $content .= "\n(";    for($j=0; $j<$fields_amount; $j++){ $row[$j] = str_replace("\n","\\n", addslashes($row[$j]) ); if (isset($row[$j])){$content .= '"'.$row[$j].'"' ;}  else{$content .= '""';}     if ($j<($fields_amount-1)){$content.= ',';}   }        $content .=")";
                //every after 100 command cycle [or at last line] ....p.s. but should be inserted 1 cycle eariler
                if ( (($st_counter+1)%100==0 && $st_counter!=0) || $st_counter+1==$rows_num) {$content .= ";";} else {$content .= ",";} $st_counter=$st_counter+1;
            }
        } $content .="\n\n\n";
    }
    $content .= "\r\n\r\n/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;\r\n/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;\r\n/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;";
    $backup_name = $backup_name ? $backup_name : $name."___(".date('H-i-s')."_".date('d-m-Y').")__rand".rand(1,11111111).".sql";
    ob_get_clean(); header('Content-Type: application/octet-stream');   header("Content-Transfer-Encoding: Binary"); header("Content-disposition: attachment; filename=\"".$backup_name."\"");
    echo $content; exit;
}      //see import.php too
?>

打印出
$command
，将其复制粘贴到shell，然后执行。