In article <[email protected]>, Rob Williscroft <[email protected]> wrote: >Aahz wrote in news:[email protected] in comp.lang.python: >> In article <[email protected]>, >> Rob Williscroft <[email protected]> wrote: >>> >>>db.execute( ''' >>> update "sessions" set "uid" = ? >>> where "uid" = ? >>> and exists( >>> select * from "users" where "uid" = ? >>> ) >>> ''', >>> (v['uid'],s.SID, v['uid']) >>> ) >> >> This will be more efficient if you do "select uid from users". > >What will be more efficient ? > >Do you mean the "select * ..." or do you want to take the exists >sub-query out and put it in a python if ?
"select uid" will be more efficient than "select *", although I suppose I could be wrong about that given how little I know about current query optimizers. -- Aahz ([email protected]) <*> http://www.pythoncraft.com/ "It is easier to optimize correct code than to correct optimized code." --Bill Harlan -- http://mail.python.org/mailman/listinfo/python-list
