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. Thanks. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
