From: Hélder M. Vieira <hmv@mail.telepac.pt>
To: pgsql-sql@postgresql.org
Subject: max() unexpected type conversion
Date: Mon, 21 Nov 2005 12:47:40 -0000
Message-ID: <000901c5ee99$c275e380$580bfea9@hmv02> (raw)
Hello.
I'm having some trouble with an unexpected conversion performed by the max()
function.
If max() operates on a 'varchar' type column, the result appears with 'text'
type.
Should I expect this behaviour in the current and later versions ?
I mention this because I'm using ODBC in VB, and this type conversion has a
bad outcome, because 'text' columns require a specific treatment (a second
reading of the column contents returns null). Therefore, if this conversion
is beeing made as a result of a design option, I'll have to use a different
approach (something like 'select ... order by ... desc limit 1').
A small sample follows, giving a 'text' type result:
create table test
(
testcol varchar(4) not null
);
insert into test (testcol) values ('A');
insert into test (testcol) values ('A');
insert into test (testcol) values ('B');
insert into test (testcol) values ('B');
insert into test (testcol) values ('C');
insert into test (testcol) values ('C');
select max(testcol) from test;
Thank you
Hélder M. Vieira
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To: pgsql-sql@postgresql.org
Cc: hmv@mail.telepac.pt
Subject: Re: max() unexpected type conversion
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