Re: Using ORDER BY with UPDATE CURSORS (SE 5.1)

javi@psi.ernet.in (javeed anwar t) wrote: > >Friends, > >I am facing a problem related to locking in INFORMIX SE 5.1. >When I DECLARE a CURSOR FOR UPDATE using ORDER BY, at the time of >opening, the Error is -365. This prevents me from using ORDER BY >with UPDATE CURSOR. Pls explain some way to get out of this >problem. > >Javeed > Well, this is a feature - not a bug. It simply is not possible to use an ORDER BY-Clause in an Update-Cursor. This has to do with locking problems. For short: If you are declaring a update-cursor, the server puts U-locks on the read pages(rows). If you are using Order by, the server creates temporary tables for doing the sort (in most cases); therefore it's of no use the put locks (and afterwards do the update) on the temp-table. This is why each cursor creating a temp-table cannot be an update-cursor. Temp-tables are created for ORDER BY, DISTINCT, GROUP BY and UNION. Peter