In article <xns9c09513903e8frtwfreenetremovec...@216.196.109.145>, Rob Williscroft <r...@freenet.co.uk> wrote: >Aahz wrote in news:guao50$1j...@panix3.panix.com in comp.lang.python: >> In article <xns9c08e179b66d8rtwfreenetremovec...@216.196.109.145>, >> Rob Williscroft <r...@freenet.co.uk> 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 (a...@pythoncraft.com) <*> 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
