Warning: Undefined array key "user_id" in C:\xampp\htdocs\PEC_old\Tram\list_tram.php on line 7

Warning: Undefined array key "hopdong_ma" in C:\xampp\htdocs\PEC_old\Tram\list_tram.php on line 8

Fatal error: Uncaught mysqli_sql_exception: Unknown column 'tbl_hopdong.HopDong_ma' in 'where clause' in C:\xampp\htdocs\PEC_old\Tram\list_tram.php:18 Stack trace: #0 C:\xampp\htdocs\PEC_old\Tram\list_tram.php(18): mysqli->query('SELECT tbl_tram...') #1 {main} thrown in C:\xampp\htdocs\PEC_old\Tram\list_tram.php on line 18