select data from database Mysql query

Question

tbl_pack_service;
+-------+---------+------------+
| ps_id | pack_id | service_id |
+-------+---------+------------+
|     1 |       1 |          1 |
|     2 |       1 |          2 |
|     3 |       2 |          1 |
|     4 |       2 |          2 |
|     5 |       2 |          3 |
|     6 |       2 |          4 |
|     7 |       2 |          5 |
|     8 |       3 |          1 |
|     9 |       3 |          2 |
|    10 |       3 |          3 |
|    11 |       3 |          4 |
+-------+---------+------------+

ps_id is primary key i am tying to make dynamic select list in php i want a mysql query that can give service id which do not match with particular pack_id

like i have service_id 1,2,3,4,5 when i should select pack_id=1 then 3,4,5 should be displayed and when i should select pack_id=2 then nothing should be displayed as it has all the 5 services. thanks..

Answer 1

There are a few ways to handle this. The easiest is with a NOT IN subquery:

SELECT DISTINCT service_id
FROM 
  tbl_pack_service
WHERE service_id NOT IN (SELECT service_id FROM tbl_pack_service WHERE pack_id = 1)