Ow Mun Heng wrote:
On Sun, 2006-08-20 at 19:59 +1000, chris smith wrote:
On 8/20/06, Ow Mun Heng <[EMAIL PROTECTED]> wrote:
I'm have a query like so
select
A,
index_A
from
tableA
join tableB
on tableB.indexA = tableA.indexA
select
A,
index_A
from
tableA
join tableB
on tableB.A = tableA.A
whcih would be more efficient? using the where clause which uses the
index or the one which isn't index?
If you join using the field that is indexed, this will use an index.
If you join using the field that isn't indexed, it can't use an index.
I take it that that means yes, it's more efficient performance wise to
always use an index.
Of course, same as any query ;)
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