about Efficiency

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?
thanks!

?е??ε?????? в??????select ..from ...where ..and ..and..and ..and ..select ..from
select ..from select ..from .....?Ч??
ллOn 20.09.2006 10:51, yicong wrote:

Quote:

Originally Posted by

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?

I cannot make much sense of this. Please rephrase your question and
especially provide more detail (DDL, DML).

A general remark: if you have two equivalent DML statements you can
easily check with MS tools (Profiler, Query Analyzer) which of the two
is more efficient.

Regards

robert|||yicong wrote:

Quote:

Originally Posted by

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
...