Re: need help for a where clause

If you are using MySQL you may want to look at the CASE statement in the "Control flow functions for use with SELECT Statements" it would look like SELECT CASE A.Afn WHEN 1 THEN B.Bfn1 WHEN 2 THEN B.Bfn2 WHEN 3 THEN B.Bfn3 FROM A,B IN MySQL Hope That Helps.. Phil "Alex Shi" <chpshi@eol.ca> schrieb im Newsbeitrag news:20021006234217.96557.qmail@pb1.pair.com... > Thanks! This is what I need! > > Alex Shi > > > > "Sascha Cunz" <Sascha@GaNoAn.org> ?????? > :200210070121.21657.Sascha@GaNoAn.org... > A solution on that depends strongly on how much values A.Afn would take. For > 3, it's still okay. But i wouldn't do more. > > Against what shall the B.Bfn* be checked? What Data do you want to be > returned > from the query? > > try: > > SELECT ### FROM A, B WHERE > ((A.Afn=1) AND (B.Bfn1 = ...)) OR > ((A.Afn=2) AND (B.Bfn2 = ...)) OR > ((A.Afn=3) AND (B.Bfn3 = ...)) > > where you should replace ### with things you want to select and ... with the > things you want to check. > > On more than 3 different values for A.Afn, you should use a more normalized > version of B. > > i.e.: B contains only one Bfn field and a Reference to A.Afn. > -> SELECT ### FROM A, B WHERE B.AfnRef = A.Afn AND B.Bfn = ... > > Sascha > > Am Montag, 7. Oktober 2002 00:33 schrieb Alex Shi: > > Hi, > > > > I need a where clause in following situation: > > > > Say I want to query two tables: A and B. In table A there is field > > Afn, while in table B there are 3 fields: Bfn1, Bfn2 and Bfn3. I want > > to do a query, in which the where clause must do these things: > > > > if A.Afn=1, then check value of B.Bfn1; > > if A.Afn=2, then check value of B.Bfn2; > > if A.Afn=3, then check value of B.Bfn3. > > > > So how can I create such a where clause to do this? > > Thanks in advance! > > > > Alex Shi >