Backup de toda una base de datos con PHP (tanto para MySQL como para SQL Server)

SQL Server:
$log_backup_file = "C:\Backups\TestDB_Log_Backup.bak";
$sql = "BACKUP LOG TestDB TO DISK = '".$log_backup_file."'";
$stmt = sqlsrv_query($conn, $sql);
if($stmt === false)
{
    die(print_r(sqlsrv_errors()));
}
else
{
    echo "Transaction log backed up to $log_backup_file";
}

MySQL:
$backup_file = "EDC_".date("Ymd_His").".sql";
$commands = array(
        "mysqldump --opt -h $host_name -u $user_name -p$password -v $database > $backup_file","bzip2 $backup_file"
);

// ejecución y salida de éxito o errores
foreach ( $commands as $command ) {
   system($command,$output);
   echo $output;
}