Can you show me their ids?
SELECT T1.cid FROM COURSE AS T1 JOIN ENROLLED_IN AS T2 ON T1.CID   =   T2.CID GROUP BY T2.CID HAVING COUNT ( * )    > =    5
ids refers to T1.cid; show me their ids implies a selection of unique identifiers (ids) for a certain condition; the condition being courses with enrollment count greater than or equal to 5;