Re: The keyword 'distinct' question

Kyle Campbell wrote: > > According to the BNF Grammar in the Informix Guide to SQL Syntax the > following statement should be legal: > > Select distinct ( sum (distinct <col1> ) ) from <table>> > It doesn't like the fact that I'm using nested 'distinct' key word. We > need this or we'll have to rework our logic for other queries. > > Thanks, > Kyle Campbell > kyle@alh.com The manual I have (Informix Guide to SQL: Syntax version 7.1) states on page 1-399, "You can use the DISTINCT or UNIQUE keywords once in each level of a query or subquery". That seems clear enough to me. I suspect the problem is that SQL is such a non-orthogonal language that the real BNF used by the parser is pretty incomprehensible to humans, so Informix have simplified it in their railroad diagrams and added some text qualifiers. A good reference to SQL-92 such as Melton & Simon or Canaan & Otten will have the full BNF, which is absolutely guaranteed to send you to sleep before you find the answer you want. The Informix diagrams are wonderful - I thought railroad diagrams had been forgotten since I last saw them in an old book on Pascal. -- Peter Lancashire Information Systems Specialist, Bayer plc Eastern Way, Bury St Edmunds, Suffolk, IP32 7AH, UK Tel: +44-1635-562258, Fax: +44-1635-562281 Mail: Peter.Lancashire.PL1@bayer.co.uk --- My Internet plumbing does not allow me to mail and post news together. Sorry. All opinions are my own and not those of Bayer plc. --- Join Infuse, the UK Informix User Group at http://www.infuse.co.uk/