可以如下代替,效率可能高些 SELECT Type FROM Titles group by Type having count(Distinct Pub_id)>1 或者 SELECT DISTINCT T1.Type FROM Titles T1 WHERE exists (SELECT 1 FROM Titles WHERE Type=T1.Type and Pub_id <> T1.Pub_id)
优化一下: use pubs SELECT DISTINCT T1.Type FROM Titles T1 WHERE EXISTS(SELECT 1 FROM Titles WHERE T1.Type=Type and T1.Pub_id <> Pub_id)
SELECT Type
FROM Titles
group by Type
having count(Distinct Pub_id)>1
或者
SELECT DISTINCT T1.Type FROM Titles T1
WHERE exists (SELECT 1 FROM Titles WHERE Type=T1.Type and Pub_id <> T1.Pub_id)
use pubs
SELECT DISTINCT T1.Type FROM Titles T1
WHERE EXISTS(SELECT 1 FROM Titles WHERE T1.Type=Type and T1.Pub_id <> Pub_id)