识别 SQL Server 中的等效集

Question

Following is a sample of the records that I have in a table. EntriesPerSet column contains the number of records in the table for that SET_ID . I need to establish equivalence between rows belonging to different SET_ID s. Sets will be equivalent, if and only if they contain an equal number of entries per Set, and every entry has a corresponding entry in the other set (by checking values in K1 & K2 ). In following case, SET_IDs 1 and 2 are equivalent.

SET_ID  K1  K2  EntriesPerSet
1   a   b   4
1   c   d   4
1   e   f   4
1   g   h   4
2   a   b   4
2   c   d   4
2   e   f   4
2   g   h   4
3   a   b   5
3   c   d   5
3   e   f   5
3   g   h   5
3   i   j   5
4   a   b   3
4   c   d   3
4   e   f   3
5   a   b   4
5   c   d   4
5   e   f   4
5   p   q   4

Please help me with how to do this. Thanks!

Answer 1

If you just want to know which pairs are equivalent, you can just use a common table expression to get all possible combinations, and an INTERSECT to figure out which of them overlap fully;

WITH cte AS (
 SELECT DISTINCT a.SET_ID aid, b.SET_ID bid, a.EntriesPerSet
 FROM mysets a
 JOIN mysets b ON a.EntriesPerSet = b.EntriesPerSet AND a.SET_ID < b.SET_ID
)
SELECT aid, bid FROM cte
WHERE EntriesPerSet = (
 SELECT COUNT(*) FROM (
  SELECT K1,K2 FROM mysets WHERE SET_ID=aid
  INTERSECT
  SELECT K1,K2 FROM mysets WHERE SET_ID=bid
 ) a
)

An SQLfiddle to test with .