What are the two methods of database backup?

/**
 * Subject: php-mysql 实现数据库备份.
 * User: luokakale
 * Date: 2018/11/9
 * Time: 13:31
 */

header('Content-Type:text/html;charset=utf8');
ini_set("max_execution_time", "0");//代码运行时间不限制  防止备份失败
ini_set('memory_limit', '128M');//设置内存 根据需求可以修改
date_default_timezone_set("PRC");
//创建需要保存sql文件的文件夹
$path = 'D:\SQL\databse_backup';
//定义数据库配置
$user = ''; //数据库账户
$pwd  = ''; //数据库密码
$dbname = ''; //数据库名称

//备份数据库命令地址文件
$sqladdress = 'D:\phpStudy\MySQL\bin\mysqldump.exe';

//备份指定地址
$time = time();
$path = 'D:\SQL\databse_backup'.'\\'.date("Ymd",$time);
if(!file_exists($path))
{
    mkdir($path,0777,true);
}

//备份的数据库文件名
$sqlFile = $dbname."_%date:~0,4%%date:~5,2%%date:~8,2%%time:~0,2%.sql";
//判断是否存在密码
$password = $pwd== ''?'':'  -p'.$pwd;
//拼接备份命令
$order =  $sqladdress.' --opt  -u'.$user.$password.' '.$dbname.' >'.$path.'\\'.$sqlFile;
//执行命令
exec($order);

header('Content-Type:text/html;charset=utf8');
ini_set("max_execution_time", "0");//代码运行时间不限制  防止备份失败
ini_set('memory_limit', '1024M');//设置内存 根据需求可以修改
date_default_timezone_set("PRC");
header("Content-Type:text/html;charset=utf-8");
$host="";
$user="";//账户
$password="";//密码
$dbname="";//数据库名称
$con =  mysqli_connect("$host","$user","$password","$dbname");
mysqli_select_db($con,$dbname);
$mysql= "set charset utf8;\r\n";#for mysql>=5.0
mysqli_query($con,"SET NAMES 'UTF8'");
$q1=mysqli_query($con,"show tables");
while($t=mysqli_fetch_array($q1)){
    $table=$t[0];
    $q2=mysqli_query($con,"show create table `$table`");
    $sql=mysqli_fetch_array($q2);
    $mysql.=$sql['Create Table'].";\r\n\r\n";#DDL
    $q3=mysqli_query($con,"select * from `$table`");
    while($data=mysqli_fetch_assoc($q3))
    {
        $keys=array_keys($data);
        $keys=array_map('addslashes',$keys);
        $keys=join('`,`',$keys);
        $keys="`".$keys."`";
        $vals=array_values($data);
        $vals=array_map('addslashes',$vals);
        $vals=join("','",$vals);
        $vals="'".$vals."'";
        $mysql.="insert into `$table`($keys) values($vals);\r\n";
        unset($data);
    }
    $mysql.="\r\n";
    unset($t);
}
mysqli_close($con);
$filename=date('Ymj').".sql"; //文件名为当天的日期
$time = time();
$path = 'D:\SQL\databse_backup'.'\\'.date("Ymd",$time).'\\';
// 检查目录是否存在
if(!is_dir($path)){
    // 新建目录
    mkdir($path, 0777, true);
}
$file_name = $path.$filename;
$fp = fopen($file_name,'w');
fputs($fp,$mysql);
fclose($fp);
$fp=fopen($file_name,"r");
$file_size=filesize($file_name);
header("Content-type: application/octet-stream");
header("Accept-Ranges: bytes");
header("Accept-Length: ".$file_size);
header("Content-Disposition: attachment; filename=".$filename);
//这里一定要使用echo 进行输出，否则下载的文家是空白的
echo fread($fp,$file_size);
fclose($fp);
exit;