Cross table join problem

[kurbsdude]

I have a table structure as below:

 

table 1:

x        y        value

23      12      2344

15      56      4353

18      20      3242

 

table 2:

p      q        allow

12    23      1

23    12      1

15    56      0

56    15      1

 

I need to accomplish the following

 

Select * from table1 WHERE y = 12 (ONLY IF there exist two rows in table2 (WHERE one has p = 12 and q= 23 and the other has q=12 and p = 23) AND (table2.allow = 1 for both table2.p = 12 AND table2.q=12))

 

Any suggestions?

Thanks in advance

[fenway]

Sounds like you need a few joins, and an EXISTS.