I have three tables that look like these:
PROD
Prod_ID|Desc
------------
P1|Foo1
P2|Foo2
P3|Foo3
P4|Foo4
...
RAM
Ram_ID|Desc
------------
R1|Bar1
R2|Bar2
R3|Bar3
R4|Bar4
...
PROD_RAM
Prod_ID|Ram_ID
------------
P1|R1
P2|R2
P3|R1
P3|R2
P3|R3
P4|R3
P5|R1
P5|R2
...
Between PROD and RAM there's a Many-To-Many relationship described by the PROD_RAM table.
Given a Ram_ID set like (R1,R3) I would like to find all the PROD that has exactly ONE or ALL of the RAM of the given set.
Given (R1,R3) should return for example P1,P4 and P5; P3 should not be returned because has R1 and R3 but also R2.
What's the fastest query to get all the PROD that has exactly ONE or ALL of the Ram_ID of a given RAM set?
EDIT:
The PROD_RAM table could contain relationship bigger than 1->3 so, "hardcoded" checks for count = 1 OR = 2 are not a viable solution.