Fatal error: Uncaught mysqli_sql_exception: Unknown column 'category_id' in 'where clause' in /opt/websites/offwww/commons/includes/db_functions.php:42 Stack trace: #0 /opt/websites/offwww/commons/includes/db_functions.php(42): mysqli_query() #1 /opt/websites/main/depts/avarts/school/includes/instructors.php(17): i3_get_record_sql() #2 /opt/websites/main/depts/avarts/school/index.php(198): include('...') #3 {main} thrown in /opt/websites/offwww/commons/includes/db_functions.php on line 42