Thanks everyone for your response. Dennis, that works great! Jay, I think I presume you meant (x >= 'a'). This works great too!
Thank you again! On 8/2/05, Dennis Cote <[EMAIL PROTECTED]> wrote: > Thomas Briggs wrote: > > > > > > > > > > >>However if I use something like: > >>select * from myTable where column2!=''; > >>(Takes a long time to return). > >> > >>I guess because the column in that row isn't indexed? Any > >>alternatives? > >> > >> > > > > I don't believe that indices can be used to satisfy != conditions, so > >even if the column is indexed, you always have to do a table scan to > >find rows matching the criteria. That can obviously take some time > >depending on the size of the table being scanned. > > > > -Tom > > > > > > > You can get the same effect as != using a union to combine the results > of two queries that can use the index, one using <, and the other using >. > > select * from myTable where column2 < '' > union > select * from myTable where column2 > '' > > This produces the same results as != (even skipping columns where > column2 is NULL), but uses the index to speed up locating the rows that > meet the criterion. > > I'm not sure if it really is faster in your application, but it may be > much faster if there are many rows that equal the criterion and are > skipped by using the index. If most rows are selected then there is > probably little gain. > > HTH > Dennis Cote >
