sql优化之not in

sql : select ID from awhere XX <> 0 and ID not in (select ID from b)

4万多条记录，执行了316秒，无法接受。

 

优化为：

select a.ID from a where not exists (select b.ID from b where a.ID = b.ID) and a.XX <> 0

只需0.2秒。