Re: SQL - finding next date

Is something like this too simple?

select term_id from terms where term_id > 2 order by term_starts limit 1;
or
select term_id from terms where term_starts > '2007-09-01' order by
term_starts limit 1;

depending on whether you have the term_id or the term_starts date.

Susan Cassidy

Raymond O'Donnell <rod(at)iol(dot)ie>
Sent by: pgsql-general-owner(at)postgresql(dot)org
04/11/2007 12:41 PM
Please respond to
rod(at)iol(dot)ie

To
'PostgreSQL' <pgsql-general(at)postgresql(dot)org>
cc

Subject
[GENERAL] SQL - finding next date

Hi all,

This is probably a very simple one, but I just can't see the answer and
it's driving me nuts. I have a table holding details of academic terms,
and I need an SQL query such that for any given term I want to find the
next term by starting date (or just NULL if there isn't one).

Here's the table -

CREATE TABLE terms
(
term_id serial NOT NULL,
term_name character varying(40) NOT NULL,
term_starts date NOT NULL,
term_ends date NOT NULL,
.....
)

- so, supposing I have the following data -

term_id | term_name | term_starts | ...
---------+-------------+-------------+--
1 | Spring 2007 | 2007-01-10 | ...
2 | Autumn 2007 | 2007-09-01 | ...
6 | Spring 2008 | 2008-01-06 | ...

- then for term '1' I'd like to return '2', for term '2' I'd like to
return '6', and so on.

The closest I've got is getting ALL terms that start after a given one,
but I run into trouble after that....any help will be appreciated!

Thanks in advance,

Ray.

---------------------------------------------------------------
Raymond O'Donnell, Director of Music, Galway Cathedral, Ireland
rod(at)iol(dot)ie
---------------------------------------------------------------

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

----------------------------------------------------------------------------------------------
Simply protected storage solutions ensure that your information is
automatically safe, readily available and always there, visit us at http://www.overlandstorage.com
----------------------------------------------------------------------------------------------