Question

SQL数据库中删除一个表在另一个表中不存在的记录？

比如表A和B，根据字段ID来判断，如果A.ID在B中，不存在，则删除此条记录，我用以下语句来删除，速度很慢，有没有方法能快速删除？
delete from A where ID not in
(select ID from B)

Answer 1

1. 采用not exists 执行橡此速度快delete from T_AD where not exists (select 1 from T_AD_PLAY where T_AD.N_CODE =T_AD_PLAY.N_CODE ) 2. 采含如轿用not in 执行速谈肆度慢Delete From T_AD Where N_AD Not In(Select N_AD From T_AD_PLAY)

Answer 2

delete from A where ID not in
(select distinct ID from B)

追问

请问这是什么情况A表中记录4W多条，B表中记录1.8W条

Answer 3

delete from A where not exists (select 咐前迅1 from B where A.ID = 衡此悔数b.ID)