Stuart McLachlan
stuart at lexacorp.com.pg
Wed Apr 30 21:33:20 CDT 2008
Not necessarily. Jet's Rushmore technology is pretty smart at optimising queries You can't see the optimised execution plan in Access, , but I set the tables up in SQL Server with appropriate indexes and did an execution plan there. (100 values in Table1, 3 in LKUP) In SQL Server ,my version uses a Table Scan on LKUP (which would normally be fairly small) and one Index Seek on Table1. Drew's version uses an Index Scan on Table1 and two Index Seeks on LKUP. Doing an Execution Plan on a Union of the two versions, my version's sub-branch cost 0.0446 while Drew's cost 0.0598. (34% more expensive) Cheers, Stuart On 30 Apr 2008 at 16:36, Charlotte Foust wrote: > But an Outer Join WHERE has to examine all records. A subquery has > already filtered them down. > > Charlotte Foust > > -----Original Message----- > From: accessd-bounces at databaseadvisors.com > [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Stuart > McLachlan > Sent: Wednesday, April 30, 2008 4:01 PM > To: Access Developers discussion and problem solving > Subject: Re: [AccessD] Query Question > > You can return both results and you don't need a subquery, just use an > Outer Join with > "Where": > > SELECT Table1.LookupValue,Result1,Result2 > FROM LKUP, Table1 > WHERE (RangeStart<=LookupValue AND RangeEnd>=[LookupValue]) > > Cheers, > Stuart > > > On 30 Apr 2008 at 14:04, Drew Wutka wrote: > > > Nope, a subquery will only work returning one record for one > > field...unless it's in the WHERE statement, where you can use 'IN' if > > you want. > > > > You'd have a problem reversing this by having the result fields show > > up in the main query, because then it will only run the number of > > records in LKUP, not the number in Table1. > > > > Drew > > > > -----Original Message----- > > From: accessd-bounces at databaseadvisors.com > > [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Andy Lacey > > Sent: Wednesday, April 30, 2008 12:55 PM > > To: 'Access Developers discussion and problem solving' > > Subject: Re: [AccessD] Query Question > > > > Works like a dream Drew, you're a star as ever. Is there any way of > > streamlining it to return more than 1 value from the subquery? > > Something like > > > > SELECT T1.LookupValue, (SELECT Result1, Result2 FROM LKUP WHERE > > RangeStart<=T1.LookupValue AND RangeEnd>=T1.LookupValue) FROM Table1 > > as T1 > > > > Only I know that doesn't work cos I've tried it. Says something about > > the EXISTS keyword, and I don't know about that. > > > > -- Andy Lacey > > http://www.minstersystems.co.uk > > > > > > > > >-----Original Message----- > > >From: accessd-bounces at databaseadvisors.com > > >[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Drew Wutka > > >Sent: 30 April 2008 17:26 > > >To: Access Developers discussion and problem solving > > >Subject: Re: [AccessD] Query Question > > > > > > > > >If your database is properly indexed yes. They do great. > > > > > >Drew > > > > > >-----Original Message----- > > >From: accessd-bounces at databaseadvisors.com > > >[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Andy Lacey > > >Sent: Wednesday, April 30, 2008 11:02 AM > > >To: Access Developers discussion and problem solving > > >Subject: Re: [AccessD] Query Question > > > > > >There you see, that's just the sort of thing I had in mind. > > >Thanks Drew. I just knew the answer was something like this but > > >couldn't have come up with the syntax. Do these subqueries perform ok > > > >though? > > > > > >-- > > >Andy Lacey > > >http://www.minstersystems.co.uk > > > > > > > > > > > >The information contained in this transmission is intended only for > > >the person or entity to which it is addressed and may contain II-VI > > >Proprietary and/or II-VI Business Sensitive material. 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