Re: The job of a relational DBMS
Date: Wed, 2 Dec 2009 16:48:40 +0100
"Shakespeare" <whatsin_at_xs4all.nl> a écrit dans le message de news: 4b1613a0$0$22919$e4fe514c_at_news.xs4all.nl...
| Thomas Kellerer schreef:
| > Gene Wirchenko wrote on 01.12.2009 05:35:
| >> For example, a group by in SQL forces the result to be sorted by
| >> the grouping unless otherwise overridden.
| > Never has been true. Group by does *not* sort the result. Not even in
| > Oracle 8 and and certainly not for any Oracle version > 9 (and not for
| > any Postgres as well)
| > Thomas
| Never? It did at least in Oracle 7. As a well known and too many times
| used side effect. I remember having to reprogram queries because
| developed programs relied on the sort....
And you did it wrong, even in Oracle7.
Grouping needs some sort but in an internal (binary) one which may not be a user sort (any country using a language with national characters has experimented this).
Michel Received on Wed Dec 02 2009 - 09:48:40 CST