Database Backup in PHP

public function db_back_up(){
        $query = $this->database_backup('localhost', 'root', 'root1234', 'affifact');
        exit("Success!");
    }


    protected static function database_backup($host, $user, $pass, $name, $tables = '*')
    {
            $link = mysqli_connect($host, $user, $pass);
            mysqli_select_db($link, $name);
            if ($tables == '*')
            {
                $tables = [];
                $result = mysqli_query($link, 'SHOW TABLES');
                while ($row = mysqli_fetch_row($result))
                {
                    $tables[] = $row[0];
                }
            } else
            {
                $tables = is_array($tables) ? $tables : explode(',', $tables);
            }

            $return = null;
            foreach ($tables as $table)
            {
                $result = mysqli_query($link, 'SELECT * FROM ' . $table);
                $num_fields = mysqli_num_fields($result);

                $return .= 'DROP TABLE ' . $table . ';';
                $row2 = mysqli_fetch_row(mysqli_query($link, 'SHOW CREATE TABLE ' . $table));
                $return .= "\r\n" . $row2[1] . ";\r\n";

                for ($i = 0; $i < $num_fields; $i ++)
                {
                    while ($row = mysqli_fetch_row($result))
                    {
                        $return .= 'INSERT INTO ' . $table . ' VALUES(';
                        for ($j = 0; $j < $num_fields; $j ++)
                        {
                            $row[$j] = addslashes($row[$j]);
                            $row[$j] = mb_ereg_replace("n", "n", $row[$j]);
                            if (isset($row[$j]))
                            {
                                $return .= '"' . $row[$j] . '"';
                            } else
                            {
                                $return .= '""';
                            }
                            if ($j < ($num_fields - 1))
                            {
                                $return .= ',';
                            }
                        }
                        $return .= ");\r\n";
                    }
                }
                $return .= "\r\n";



            }

            $file_name = 'db-backup-' . date("d-m-y-h-i-s-A") . '.sql';
            $handle = fopen("/tmp/db_backup/" . $file_name, 'w+');
            fwrite($handle, $return);
            fclose($handle);
    }