Fatal error: Uncaught mysqli_sql_exception: Can't DROP 'imei'; check that column/key exists in C:\Apache24\htdocs\update\update_5.php:28 Stack trace: #0 C:\Apache24\htdocs\update\update_5.php(28): mysqli_query(Object(mysqli), 'alter table gs_...') #1 {main} thrown in C:\Apache24\htdocs\update\update_5.php on line 28