newbie question for return date
Hi guys, here a newbies question.
I've made a table with some action and date.
How may i query the most recent date. (I'd like to return only the record
which have the most recent date ).
Tx
In article <xEgv9.2668$h_4.374526@news20.bellglobal.com>, tviardot wrote:
Hi guys, here a newbies question.
I've made a table with some action and date.
How may i query the most recent date. (I'd like to return only the record
which have the most recent date ).
Tx
How about:
SELECT * FROM t ORDER BY d DESC LIMIT 1;
Hey a suggestion, what if PG would support the negative limit as in
select * from table limit -1 to mean limit it from the other end of
list.....
Sort of like some languages where they support
array[1] vs array[-1].
I'm not sure, but it looks like order by will sort the list which is
expensive and then
allow us to get the first chunk specified by limit.
Lee Harr wrote:
Show quoted text
In article <xEgv9.2668$h_4.374526@news20.bellglobal.com>, tviardot wrote:
Hi guys, here a newbies question.
I've made a table with some action and date.
How may i query the most recent date. (I'd like to return only the record
which have the most recent date ).
TxHow about:
SELECT * FROM t ORDER BY d DESC LIMIT 1;
---------------------------(end of broadcast)---------------------------
TIP 3: if posting/reading through Usenet, please send an appropriate
subscribe-nomail command to majordomo@postgresql.org so that your
message can get through to the mailing list cleanly
In order for your proposed result of array[-1] to be consistent/predictable,
an ORDER BY sorting action will have to be performed *anyway* (in order to
consistently return the last record(s) from the recordset), so doing an
ORDER BY field_name DESC LIMIT 1 will have the same effect.
Just my 2 cents
Terry Fielder
Network Engineer
Great Gulf Homes / Ashton Woods Homes
terry@greatgulfhomes.com
Show quoted text
-----Original Message-----
From: pgsql-general-owner@postgresql.org
[mailto:pgsql-general-owner@postgresql.org]On Behalf Of Medi Montaseri
Sent: Monday, October 28, 2002 8:13 PM
To: missive@hotmail.com
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] newbie question for return dateHey a suggestion, what if PG would support the negative limit as in
select * from table limit -1 to mean limit it from the other end of
list.....Sort of like some languages where they support
array[1] vs array[-1].
I'm not sure, but it looks like order by will sort the list which is
expensive and then
allow us to get the first chunk specified by limit.Lee Harr wrote:
In article <xEgv9.2668$h_4.374526@news20.bellglobal.com>,
tviardot wrote:
Hi guys, here a newbies question.
I've made a table with some action and date.
How may i query the most recent date. (I'd like to returnonly the record
which have the most recent date ).
TxHow about:
SELECT * FROM t ORDER BY d DESC LIMIT 1;
---------------------------(end of
broadcast)---------------------------
TIP 3: if posting/reading through Usenet, please send an appropriate
subscribe-nomail command to majordomo@postgresql.org so that your
message can get through to the mailing list cleanly---------------------------(end of
broadcast)---------------------------
TIP 2: you can get off all lists at once with the unregister command
(send "unregister YourEmailAddressHere" to
majordomo@postgresql.org)
Medi Montaseri <medi.montaseri@intransa.com> writes:
Hey a suggestion, what if PG would support the negative limit as in
select * from table limit -1 to mean limit it from the other end of
list.....
You'd hardly want that, as it would necessarily be the slowest possible
way of retrieving the rows you're after.
Instead, reverse the sort order. For example
select * from table order by datecol desc limit 1;
regards, tom lane
On Monday 28 Oct 2002 7:57 pm, tviardot wrote:
Hi guys, here a newbies question.
I've made a table with some action and date.
How may i query the most recent date. (I'd like to return only the record
which have the most recent date ).
SELECT * from table_name ORDER BY date_column DESC LIMIT 1;
If you have an index on date_column this will be almost instant. If two rows
have the same (largest) value in date_column which gets returned isn't well
defined.
--
Richard Huxton