So lets say in this case, the group that we have is groups of animals.
Lets say I have the following tables:
animal_id | attribute_id | animal
----------------------------------
1 | 1 | dog
1 | 4 | dog
2 | 1 | cat
2 | 3 | cat
3 | 2 | fish
3 | 5 | fish
id | attribute
------------------
1 | four legs
2 | no legs
3 | feline
4 | canine
5 | aquatic
Where the first table contains the attributes that define an animal, and the second table keeps track of what each attribute is. Now lets say that we run a query on some data and get the following result table:
attribute_id
------------
1
4
This data would describe a dog, since it is the only animal_id that has both attributes 1 and 4. I want to be able to somehow get the animal_id (which in this case would be 1) based on the third table, which is essentially a table that has already been generated that contains the attributes of an animal.
The third table that has 1 and 4 doesn't have to be 1 and 4. It could return 2 and 5 (for fish), or 1 and 3 (cat).
We can assume that it's result will always match one animal completely, but we don't know which one.