The only thing I know is that "EXISTS" is on the help screen as being an Obsolete command. I never use obsolete commands because I can't be sure that some day a version isn't going to come out that doesn't support the command. Karen
-----Original Message----- From: Bill Eyring <[email protected]> To: RBASE-L Mailing List <[email protected]> Sent: Wed, May 14, 2014 12:27 pm Subject: [RBASE-L] - EXISTS vs. IS NOT NULL I would like to know whether EXISTS performs better or is preferential when coding SQL rather than using IS NOT NULL. I would also like to know what your particular preference is and why. I have used the IS NOT NULL parameter for years. Recently I have tried using EXISTS which in certain instances seems to increase code performance. According to Rbase Extreme 9.5 documentation, the EXISTS parameter is only mentioned(as far as I've seen) when used in a sub-select. Can EXISTS be used outside a sub-select or not. For Example I could write this; insert into tablename1(column1, column2) sel colname3,colname4 from table2 whe colname5 IS NOT NULL Alternatively I could write; insert into tablename1(column1, column2) sel colname3,colname4 from table2 whe colname5 EXISTS Both work, although I get the feeling that EXISTS works faster. Any input would be appreciated. Bill Eyring
