$sql='SELECT * FROM '.$tbl_grade_certificate.' WHERE cat_id= (SELECT id FROM '.$tbl_grade_category.' WHERE course_code = "'.Database::escape_string($course_code).'" AND session_id = '.$session_id.' LIMIT 1 ) AND user_id='.Database::escape_string($user_id);
if (empty($session_id)) {
$session_condition = ' AND (session_id = "" OR session_id = 0 OR session_id IS NULL )';
} else {
$session_condition = " AND session_id = $session_condition";
}
$sql='SELECT * FROM '.$tbl_grade_certificate.' WHERE cat_id= (SELECT id FROM '.$tbl_grade_category.' WHERE course_code = "'.Database::escape_string($course_code).'" '.$session_condition.' LIMIT 1 ) AND user_id='.Database::escape_string($user_id);