请教高手这几种写法有什么区别
1.SELECT *
FROM RS_YGB
WHERE (NOT EXISTS
(SELECT oabh
FROM temp_rs_yg
WHERE oabh = rs_ygb.ygbh))
ORDER BY YGBH
2.SELECT *
FROM RS_YGB
WHERE (YGBH NOT IN
(SELECT oabh
FROM temp_rs_yg))
ORDER BY YGBH
3.SELECT *
FROM RS_YGB
WHERE (YGBH NOT IN
(SELECT oabh
FROM temp_rs_yg
WHERE oabh IS NOT NULL))
ORDER BY YGBH
本人测试1和3结果相同,请高人就效率和结果解疑