摘要：
SELECT c.userId, c.userName FROM (SELECT * FROM a UNION SELECT * FROM b) c WHERE c.userId NOT IN (SELECT b.`userId` FROM a JOIN b ON a... 阅读全文
摘要：
1 SELECT 2 c.userId, 3 c.userName 4 FROM 5 (SELECT 6 * 7 FROM 8 a 9 UNION 10 SELECT 11 * 12 FROM 13 b) c 14 WHERE c.userId NOT IN 15 (SELECT 16 b.`use 阅读全文