[prev in list] [next in list] [prev in thread] [next in thread]
List: postgresql-general
Subject: Re: [GENERAL] COALESCE function
From: mike <mike () thegodshalls ! com>
Date: 2006-12-31 6:10:29
Message-ID: 1167545429.25375.4.camel () localhost ! localdomain
[Download RAW message or body]
Based on the below each row could end up returning a different data type
compared to a previous row for that column.
SELECT COALESCE( CAST(f.number as varchar(100)) , f.name) FROM....
Whatever f.name is set to in terms of the max length of varchar, if any,
is what f.number should be cast to.
mike
On Sun, 2006-12-31 at 00:44 -0500, Kevin Hunter wrote:
> Hello All,
>
> Attempting to select two different column types with COALESCE returns
> this error:
>
> ERROR: COALESCE types smallint and character varying cannot be matched
>
> Attempting the same thing with a CASE statement returns a similar error:
>
> ERROR: CASE types smallint and character varying cannot be matched
>
> I also checked Oracle's NVL command, and it throws a similar error.
> Clearly, I'm not supposed to intermix two different column types into a
> SELECT statement. This is because the engine needs to return a set
> given the criteria, and it's difficult to do that with criteria that
> /depends on the data/, yes?
>
> Could someone explain a/the more formal reason why I can't do what I'm
> trying to do?
>
> The relevant part of my SELECT statement:
>
> SELECT
> ...,
> COALESCE(f.number, f.name),
> ...
> FROM
> ...,
> field AS f,
> ...
> WHERE
> ...
> ;
>
> f.number ∈ SMALLINT
> f.name ∈ CHARACTER VARYING
>
> Thank you in advance!
>
> Kevin
>
> P.S. If something gets lost in bit/encoding translation, ∈ = "Element Of"
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
> http://archives.postgresql.org/
---------------------------(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
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic