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* How to increase precision?
@ 2003-05-02 21:38 Katka a Daniel Dunajsky <daniel_katka@hotmail.com>
0 siblings, 3 replies; 4+ messages in thread
From: Katka a Daniel Dunajsky @ 2003-05-02 21:38 UTC (permalink / raw)
To: pgsql-sql
Hello all,
this is a newbie question:
How to increase the precision of calculations in posgresql?
When I run this query:
select 5/2;
I get:
?column?
--------
2
It should be 2.5 shouldn't it?
Thank you for your time.
Daniel
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^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: How to increase precision?
@ 2003-05-02 22:13 Steve Crawford <scrawford@pinpointresearch.com>
parent: Katka a Daniel Dunajsky <daniel_katka@hotmail.com>
2 siblings, 0 replies; 4+ messages in thread
From: Steve Crawford @ 2003-05-02 22:13 UTC (permalink / raw)
To: Katka a Daniel Dunajsky <daniel_katka@hotmail.com>; pgsql-sql
It's assuming INTs and doing int division. Make one a numeric/real or
explicitly cast:
steve=# select 5/2;
?column?
----------
2
(1 row)
steve=# select 5./2;
?column?
----------
2.5
(1 row)
Cheers,
Steve
On Friday 02 May 2003 2:38 pm, Katka a Daniel Dunajsky wrote:
> Hello all,
>
> this is a newbie question:
>
> How to increase the precision of calculations in posgresql?
>
> When I run this query:
>
> select 5/2;
>
> I get:
>
> ?column?
> --------
> 2
>
> It should be 2.5 shouldn't it?
>
> Thank you for your time.
>
> Daniel
>
>
>
>
>
>
> _________________________________________________________________
> Help STOP SPAM with the new MSN 8 and get 2 months FREE*
> http://join.msn.com/?page=features/junkmail
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: How to increase precision?
@ 2003-05-02 22:32 Josh Berkus <josh@agliodbs.com>
parent: Katka a Daniel Dunajsky <daniel_katka@hotmail.com>
2 siblings, 0 replies; 4+ messages in thread
From: Josh Berkus @ 2003-05-02 22:32 UTC (permalink / raw)
To: Katka a Daniel Dunajsky <daniel_katka@hotmail.com>; pgsql-sql
Hey Katka,
> How to increase the precision of calculations in posgresql?
>
> When I run this query:
>
> select 5/2;
>
> I get:
>
> ?column?
> --------
> 2
>
> It should be 2.5 shouldn't it?
Nope! You're thinking like a normal person, not like a database engineer.
Translated, here's what you told the database:
Give me INTEGER 5 / INTEGER 2
and the database told you:
INTEGER 2
if you'd asked, the database would also have happily told you:
REMAINDER 1
What you really wanted to ask the database was:
Give me NUMERIC 5 / NUMERIC 2
or in SQL:
SELECT 5::NUMERIC/2::NUMERIC
At which point you will get
2.5000 (NUMERIC)
Look for a general book on SQL databases, which should be able to give you a
primer on data types and casting.
--
-Josh Berkus
Aglio Database Solutions
San Francisco
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: How to increase precision?
@ 2003-05-02 22:42 Stephan Szabo <sszabo@megazone23.bigpanda.com>
parent: Katka a Daniel Dunajsky <daniel_katka@hotmail.com>
2 siblings, 0 replies; 4+ messages in thread
From: Stephan Szabo @ 2003-05-02 22:42 UTC (permalink / raw)
To: Katka a Daniel Dunajsky <daniel_katka@hotmail.com>; +Cc: pgsql-sql
On Fri, 2 May 2003, Katka a Daniel Dunajsky wrote:
> this is a newbie question:
>
> How to increase the precision of calculations in posgresql?
>
> When I run this query:
>
> select 5/2;
>
> I get:
>
> ?column?
> --------
> 2
>
> It should be 2.5 shouldn't it?
It's doing integer division since both arguments are integers. You'll need
to make one of them something like float, double or numeric.
For example, queries like:
select 5./2;
select 5/cast(2 as float);
etc... don't do integer division because one of
the arguments isn't typed as an integer type.
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2003-05-02 22:42 UTC | newest]
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-- links below jump to the message on this page --
2003-05-02 21:38 How to increase precision? Katka a Daniel Dunajsky <daniel_katka@hotmail.com>
2003-05-02 22:13 ` Steve Crawford <scrawford@pinpointresearch.com>
2003-05-02 22:32 ` Josh Berkus <josh@agliodbs.com>
2003-05-02 22:42 ` Stephan Szabo <sszabo@megazone23.bigpanda.com>
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