Re: FWD/BACK/GOTO ? / ESQL

In article <mbehna.56.000B7B24@promus.com> mbehna@promus.com writes: glidden@informix.com has emailed me regarding my suggestion. I repeat his comments as they don't seem to have made in into the thread. My suggestion (use rowid -1 or rowid + 1 ) will not work for Online as rowid is a function of extent & offset within extent. This means that even in a newly clustered table there may be discontinuities in rowid values and my suggestion would be unsound. To implement my suggestion, and it starts to look a bit uninteresting, you would have to add a column to hold the position of a row in a particular sort sequence. You could even add several such columns, index them, write programs to keep them current and bring a large system to a halt fairly quickly. I give up. :( I also do some ORACLE work (booH!!!) and note that their ROW SEQUENCE NUMBER is the same as Informix Online, a composite value built from the physical storage location of a row (File + Page + Offset ). I think that the original root of this thread, "how do you scroll backwards or forwards out of the bounds of a cursor?", is (for good reason?), only a feature of smaller PC based Flat file & RDBMS. Codd would Cringe! ----- I'll bet it makes sense in IMS and most other Hierarchical DBMS! -- Charlie ------------------------------------------------------------------------------- Charlie Hussey Edina Software Limited Email: charlie@edina.demon.co.uk 4 James Street Fax: +44 (0) 31 669 9092 Edinburgh EH15 2DS Scotland, UK -------------------------------------------------------------------------------