返回所有出现不止一次的记录

Question

I have a table that looks like this:

ID     UNIT_ID     MEMBER_ID    CORPORATION_ID
16     1138        0            2
18     1139        0            2
47     7007        0            3
56     1672        0            7

I need two queries: one that will give me a distinct list of the corporation_ids that occur ONCE in this table, and one that returns all corporation_ids that occurs 2 or more times.

I will be passing in a sequence of corporation_ids that should be the basis of the search, basically an IN (2,3,7).

Query 1 should return 3 and 7 (both are single entry corporation_ids) Query 2 should return 2 (multiple entry corporation_id)

The reason for not doing a JOIN is that the list of corporations are in one database, and the connections (this table) is in another.

Thanks for any help I can get!

Answer 1

Post aggregation check is useful here

SELECT corporation_id FROM t WHERE ID IN(2,3,7)
GROUP BY corporation_id
HAVING COUNT(*)=1

SELECT corporation_id FROM t WHERE ID IN(2,3,7)
GROUP BY corporation_id
HAVING COUNT(*)>1