显示订阅了 Football 和 Chess 但未订阅 Tennis 的员工的详细信息。
SELECT *
FROM employee
WHERE empid IN (SELECT empid
FROM subscription
WHERE facid IN (SELECT facid
FROM facility
WHERE facility = 'Chess'
OR facility = 'Football'))
AND empid NOT IN (SELECT empid
FROM subscription
WHERE facid = (SELECT facid
FROM facility
WHERE facility = 'Tennis'));
SELECT DISTINCT empid
FROM subscription
WHERE facid IN (SELECT facid
FROM facility
WHERE facility = 'Chess'
OR facility = 'Football')
AND facid != (SELECT facid
FROM facility
WHERE facility = 'Tennis');
第一个给出正确的结果。