select tsf.aa,
(
select distinct 1 from a,b,c
where a.id = tsf.id
and b.cc = tsf.cc
and c.cc = tsf.cc
)xx
from tsf
inner join tss on tss.id = tsf.id
where tss.s = 1
and tss.date > getdate() and tss.date < getdate()
将子查询xx 转换为left join 性能能否提升，想问一下，类似于这样的子查询，怎么编写sql 才能提升 查询性能
