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比较查询速度----
select a,b=(select sum(c) from t1 where t.a=t1.a)
from t
和
select a,d.h
from t
inner join
(select a,sum(c) as h from t1) D on t.a=t1.a
from t
和
select a,d.h
from t
inner join
(select a,sum(c) as h from t1) D on t.a=t1.a
...全文
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shuiniu 2003-12-22
ctrl+L
victorycyz 2003-12-22
我认为这样更好：
select a,sum(c) as h
from t
inner join t1 on t.a=t1.a
group by t.a
select a,sum(c) as h
from t
inner join t1 on t.a=t1.a
group by t.a
azsoft 2003-12-22
如何比较？
cgsun 2003-12-22
ctrl+L