SQL Select only rows where exact multiple relationships exist

Question

This is closely related to this question, but adds another requirement.

Given a parent table \'parent\'

╔════════════╦════════╗
║ PARENT_ID  ║ NAME           


        

Answer 1

SELECT PARENT_ID
FROM rel
GROUP BY PARENT_ID
HAVING
  COUNT(PROP_ID)=2 AND
  COUNT(DISTINCT case when PROP_ID IN ( 1, 5 ) then PROP_ID end)=2

This will select all PARENT_ID that have exactly two rows, with exactly two, non duplicated, PROP_ID that match.

Answer 2

Hope this will help you:

SELECT p.PARENT_ID , r.PROP_ID FROM rel r LEFT JOIN parent p ON p.PARENT_ID = r.PARENT_ID WHERE r.PROP_ID = 5 OR r.PROP_ID = 1

Answer 3

Assuming (PARENT_ID, PROP_ID) is unique:

SELECT r1.PARENT_ID
FROM rel r1
INNER JOIN rel r2 ON r1.PARENT_ID = r2.PARENT_ID AND r2.PROP_ID = 5 
INNER JOIN rel r3 ON r1.PARENT_ID = r3.PARENT_ID AND r3.PROP_ID = 1
GROUP BY r1.PARENT_ID
HAVING COUNT(*) = 2

Or,

SELECT parent.PARENT_ID
FROM parent
INNER JOIN
(
    SELECT PARENT_ID
    FROM rel
    WHERE PROP_ID IN (1,5)
    GROUP BY PARENT_ID
    HAVING COUNT(*) = 2
) good ON parent.PARENT_ID = good.PARENT_ID
LEFT OUTER JOIN rel bad ON parent.PARENT_ID = bad.PARENT_ID 
    AND bad.PROP_ID NOT IN (1,5)
WHERE bad.PARENT_ID IS NULL

Or even,

SELECT DISTINCT parent.PARENT_ID
FROM parent
INNER JOIN rel r2 ON parent.PARENT_ID = r2.PARENT_ID AND r2.PROP_ID = 5 
INNER JOIN rel r3 ON parent.PARENT_ID = r3.PARENT_ID AND r3.PROP_ID = 1
LEFT OUTER JOIN rel r0 ON parent.PARENT_ID = r0.PARENT_ID 
    AND r0.PROP_ID NOT IN (1,5)
WHERE r0.PARENT_ID IS NULL

Answer 4

This query is true even if (PARENT_ID, PROP_ID) is not unique:

SELECT PARENT_ID FROM rel WHERE
PROP_ID IN (5,1) AND 
PARENT_ID NOT IN (SELECT DISTINCT PARENT_ID FROM rel WHERE PROP_ID NOT IN (5,1))
GROUP BY PARENT_ID HAVING COUNT(DISTINCT PROP_ID) = 2