https://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html#function_coalesce

COALESCE()

IN

NOT_IN

NOT_LIKE

FIND_IN_SET

Example: select * from users where (find_in_set (5, access_string) > 0);

will return position of the key if found in string. else will return 0 for not found or NULL if field is NULL