Question

I wanna know a single MySQL query for solving this problem:

I have a table that consists of member ids and location ids..

_________________________________________________________
|      |                        |                        |
| ID   |  Member Id             |       Location         |
|______|________________________|________________________|
|      |                        |                        |
| 1    |    2371                |           7            |
|      |                        |                        |
| 2    |    5123                |          10            |
|      |                        |                        |
| 3    |    2371                |           9            |
|      |                        |                        |
| 4    |    5123                |           9            |
|      |                        |                        |
| 5    |     565                |           9            |
|      |                        |                        |
| 6    |    2371                |           5            |
|      |                        |                        |
| 7    |    5123                |           6            |
|      |                        |                        |
|______|________________________|________________________|

Another table consists of all the locations data:

__________________________________________________
|                        |                        |
|  Location Id           |       Location Name    |
|________________________|________________________|
|                        |                        |
|      1                 |           ABC          |
|                        |                        |
|      2                 |           BCD          |
|                        |                        |
|      3                 |           CDE          |
|                        |                        |
|      4                 |           DEF          |
|                        |                        |
|      5                 |           EFG          |
|                        |                        |
|      6                 |           GHI          |
|                        |                        |
|      7                 |           HIJ          |
|                        |                        |
|      8                 |           IJK          |
|                        |                        |
|      9                 |           JKL          |
|________________________|________________________|

I wanna find all location ids from the table where member id 2371 is not present. How can I find this in single query? I know I can do it if I break the query into two pieces.. Like array of all locations.. and array of all locations where member id exist. Then using !in_array function of PHP

Thanks for your time and help in advance.

Answer 1

You can find all locations that member 2371 is in by doing:

SELECT location 
FROM memberlocation
WHERE memberid = 2371

You can find all other locations (the ones you want) by:

SELECT * 
FROM location 
WHERE locationid NOT IN 
    ( SELECT location 
      FROM memberlocation
      WHERE memberid = 2371)