Thread: Making NULL entries appear first when ORDER BY ASC
Hi, I have the following table, with the query below to list entries from it
where start_date IS NOT NULL:
CREATE TABLE onp_crm_activity_log(
id serial PRIMARY KEY,
start_date timestamp,
start_time timestamp,
end_time timestamp,
title varchar NOT NULL
);
SELECT start_date, start_time, end_time, title
FROM onp_crm_activity_log
WHERE start_date IS NOT NULL
ORDER BY start_date ASC, start_time ASC;
start_date | start_time | end_time | title
---------------------+---------------------+---------------------+-----------2005-02-03 00:00:00 | 2005-02-03 08:00:00
| | Something2005-02-03 00:00:00 | 2005-02-03 09:00:00 | 2005-02-03 12:00:00 | Something2005-02-03
00:00:00| | | Something
Now, as you see, touples with NULL in the "start_time"-field appear "after"
the others. I would like to make all entries where start_time IS NULL apear
*before* all the others. Any idea how to achieve this?
--
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
gpg public_key: http://dev.officenet.no/~andreak/public_key.asc
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while you weren't looking, Andreas Joseph Krogh wrote: > Any idea how to achieve this? ... ORDER BY coalesce(start_date, '1900-01-01') ASC , coalesce(start_time, '1900-01-01') ASC; /rls -- :wq
On Wed, 2005-02-16 at 00:55 +0000, Andreas Joseph Krogh wrote: > SELECT start_date, start_time, end_time, title > FROM onp_crm_activity_log > WHERE start_date IS NOT NULL > ORDER BY start_date ASC, start_time ASC; > > start_date | start_time | end_time | title > ---------------------+---------------------+---------------------+----------- > 2005-02-03 00:00:00 | 2005-02-03 08:00:00 | | Something > 2005-02-03 00:00:00 | 2005-02-03 09:00:00 | 2005-02-03 12:00:00 | Something > 2005-02-03 00:00:00 | | | Something > > > Now, as you see, touples with NULL in the "start_time"-field appear "after" > the others. I would like to make all entries where start_time IS NULL apear > *before* all the others. Any idea how to achieve this? how about ORDER BY start_date , COALESCE(start_time,'0001-01-01 00:00:00'::timestamp) ? gnari
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > Now, as you see, touples with NULL in the "start_time"-field > appear "after" the others. I would like to make all entries > where start_time IS NULL apear *before* all the others. ORDER BY start_date, CASE WHEN start_time IS NULL THEN 0 ELSE 1 END, start_time - -- Greg Sabino Mullane greg@turnstep.com PGP Key: 0x14964AC8 200502152309 http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 -----BEGIN PGP SIGNATURE----- iD8DBQFCEseYvJuQZxSWSsgRAlipAJwKAyqAyLbo9hfpoWkz0SOlTY3feACfa+ng DqNY4DAJ5TeeGQbI+smNilg= =LRhP -----END PGP SIGNATURE-----
> > Now, as you see, touples with NULL in the "start_time"-field appear "after" > the others. I would like to make all entries where start_time IS NULL apear > *before* all the others. Any idea how to achieve this? SELECT start_date, start_time, end_time, title FROM onp_crm_activity_log WHERE start_date IS NOT NULL ORDER BY start_date ASC, start_time IS NOT NULL ASC, start_time ASC; This assumes you want the NULL start times first within a particular date. Otherwise change the order in the ORDER BY clause.
On Wednesday 16 February 2005 04:47, Bruno Wolff III wrote: > > Now, as you see, touples with NULL in the "start_time"-field appear > > "after" the others. I would like to make all entries where start_time IS > > NULL apear *before* all the others. Any idea how to achieve this? > > SELECT start_date, start_time, end_time, title > FROM onp_crm_activity_log > WHERE start_date IS NOT NULL > ORDER BY start_date ASC, start_time IS NOT NULL ASC, start_time ASC; > > This assumes you want the NULL start times first within a particular > date. Otherwise change the order in the ORDER BY clause. Thanks! This si, IMO, the cleanest solution as it doesn't involve any COALESCE. -- Andreas Joseph Krogh <andreak@officenet.no> Senior Software Developer / Manager gpg public_key: http://dev.officenet.no/~andreak/public_key.asc ------------------------+---------------------------------------------+ OfficeNet AS | The most difficult thing in the world is to | Hoffsveien 17 | know how to do a thing and to watch | PO. Box 425 Skøyen | somebody else doing it wrong, without | 0213 Oslo | comment. | NORWAY | | Phone : +47 22 13 01 00 | | Direct: +47 22 13 10 03 | | Mobile: +47 909 56 963 | | ------------------------+---------------------------------------------+
How would one know from the reference material that it is possible to include IS NOT NULL in an ORDER BY clause? Similarly, other than the FAQ, I've never been able to tell from the SELECT documentation why ORDER BY random() works. -tfo -- Thomas F. O'Connell Co-Founder, Information Architect Sitening, LLC http://www.sitening.com/ 110 30th Avenue North, Suite 6 Nashville, TN 37203-6320 615-260-0005 On Feb 16, 2005, at 3:39 AM, Andreas Joseph Krogh wrote: > On Wednesday 16 February 2005 04:47, Bruno Wolff III wrote: >>> Now, as you see, touples with NULL in the "start_time"-field appear >>> "after" the others. I would like to make all entries where >>> start_time IS >>> NULL apear *before* all the others. Any idea how to achieve this? >> >> SELECT start_date, start_time, end_time, title >> FROM onp_crm_activity_log >> WHERE start_date IS NOT NULL >> ORDER BY start_date ASC, start_time IS NOT NULL ASC, start_time ASC; >> >> This assumes you want the NULL start times first within a particular >> date. Otherwise change the order in the ORDER BY clause. > > Thanks! This si, IMO, the cleanest solution as it doesn't involve any > COALESCE.
Well, for the docs to list every possible conditional-statement for an order by clause would just about include them all, so be all the more confusing. Sub queries, IN, aggregate functions, aliases.. the list goes on and on. I'd say that knowledge (that most conditionals can be used in an order-by or group-by) should be implicit once a person has a basic understanding of the language. Thomas F.O'Connell wrote: > How would one know from the reference material that it is possible to > include IS NOT NULL in an ORDER BY clause? > > Similarly, other than the FAQ, I've never been able to tell from the > SELECT documentation why ORDER BY random() works. > > -tfo > > -- > Thomas F. O'Connell > Co-Founder, Information Architect > Sitening, LLC > http://www.sitening.com/ > 110 30th Avenue North, Suite 6 > Nashville, TN 37203-6320 > 615-260-0005 > > On Feb 16, 2005, at 3:39 AM, Andreas Joseph Krogh wrote: > >> On Wednesday 16 February 2005 04:47, Bruno Wolff III wrote: >> >>>> Now, as you see, touples with NULL in the "start_time"-field appear >>>> "after" the others. I would like to make all entries where >>>> start_time IS >>>> NULL apear *before* all the others. Any idea how to achieve this? >>> >>> >>> SELECT start_date, start_time, end_time, title >>> FROM onp_crm_activity_log >>> WHERE start_date IS NOT NULL >>> ORDER BY start_date ASC, start_time IS NOT NULL ASC, start_time ASC; >>> >>> This assumes you want the NULL start times first within a particular >>> date. Otherwise change the order in the ORDER BY clause. >> >> >> Thanks! This si, IMO, the cleanest solution as it doesn't involve any >> COALESCE. > > > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Don't 'kill -9' the postmaster > > >
On Wed, Feb 23, 2005 at 13:54:50 -0600, "Thomas F.O'Connell" <tfo@sitening.com> wrote:
> How would one know from the reference material that it is possible to
> include IS NOT NULL in an ORDER BY clause?
>
> Similarly, other than the FAQ, I've never been able to tell from the
> SELECT documentation why ORDER BY random() works.
From the SELECT command documentation:
SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] * | expression [ AS output_name ] [, ...] [ FROM from_item
[,...] ] [ WHERE condition ] [ GROUP BY expression [, ...] ] [ HAVING condition [, ...] ] [ { UNION | INTERSECT
|EXCEPT } [ ALL ] select ] [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ] [ LIMIT { count | ALL }
] [ OFFSET start ] [ FOR UPDATE [ OF table_name [, ...] ] ]
Notice that for ORDER BY you can supply an expression. That should be a big
clue why you can use IS NOT NULL and random() in an ORDER BY clause.
Yup. Got it. Wasn't thinking clearly about what expression meant. Thanks! -tfo -- Thomas F. O'Connell Co-Founder, Information Architect Sitening, LLC http://www.sitening.com/ 110 30th Avenue North, Suite 6 Nashville, TN 37203-6320 615-260-0005 On Feb 23, 2005, at 2:33 PM, Bruno Wolff III wrote: > On Wed, Feb 23, 2005 at 13:54:50 -0600, > "Thomas F.O'Connell" <tfo@sitening.com> wrote: >> How would one know from the reference material that it is possible to >> include IS NOT NULL in an ORDER BY clause? >> >> Similarly, other than the FAQ, I've never been able to tell from the >> SELECT documentation why ORDER BY random() works. > > From the SELECT command documentation: > SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] > * | expression [ AS output_name ] [, ...] > [ FROM from_item [, ...] ] > [ WHERE condition ] > [ GROUP BY expression [, ...] ] > [ HAVING condition [, ...] ] > [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ] > [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ] > [ LIMIT { count | ALL } ] > [ OFFSET start ] > [ FOR UPDATE [ OF table_name [, ...] ] ] > > Notice that for ORDER BY you can supply an expression. That should be > a big > clue why you can use IS NOT NULL and random() in an ORDER BY clause.