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Posted by Ed Murphy on 09/20/06 16:05
yicong wrote:
> I want to select one field from a table,but it should on some conditions
> which refer to 5 table ,such as A.FILED1=B.FIELD1 AND B.FIELD2=C.FIELD3 AND
> ....
> Should I use case "select sum(a.amount) from a,b,c,... where
> a.field1=b.field1 and b.field2=c.field2 and ..." or "select sum(a.amount)
> from select b.field1 from select c.field2 from...."?And which case is more
> efficiency?
select sum(a.amount)
from a
join b on a.field1 = b.field1
join c on b.field2 = c.field2
...
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