Re: Top N within groups?

Martijn van Oosterhout wrote:
> On Fri, Jul 11, 2008 at 01:24:28PM +1000, Klint Gore wrote:
> > [thinking out loud]
> > Can someone familiar with the source for DISTINCT ON comment on how hard
> > it would be to add another parameter to return more than one row?
>
> From a programming point of view, it wouldn't be too hard. However,
> deciding what syntax to use is a another question entirely. I think
> your suggestion of FOR isn't good (ambiguous syntax, 'for' could be a
> column name), but I can't think of a better one.
>
'for' is a reserved key word so can't be a column name.

http://www.postgresql.org/docs/8.3/interactive/sql-keywords-appendix.html

postgres=# create table foo (for int);
ERROR: syntax error at or near "for"

The worst I think you could get would be
select distinct on ("for") for 4 "for" from table4 for update;

but even then, I think the parser could work out what you want.

klint.

--
Klint Gore
Database Manager
Sheep CRC
A.G.B.U.
University of New England
Armidale NSW 2350

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