请问，如何优化not in？
这条sql应该如何优化，使其效率最高呢？

select DISTINCT(name) from AA where name not in((select name from BB) union (select name from CC))



[解决办法]

select distinct name
from AA as tmp
where not exists(select 1 from BB where name=tmp.name) and
not exists(select 1 from CC where name=tmp.name)