Thread: String Concatenation

----- Original Message -----

From: Luiz K. Matsumura

To: pgsql-novice@postgresql.org

Sent: Friday, July 23, 2004 9:00 AM

Subject: [NOVICE] String Concatenation

I want to concatenate 2 fields :

tpmov char(4)  | dsmov char(10)

---------------+----------------

AB             | SOMETHING

 

If I do:

 

SELECT tpmov || dsmov as History ...

 

if the field tpmov has a fixed lenght of char(4) the result

expected (I suppose) may be

 

History

--------------

AB  SOMETHING

 

But Postgres returns

 

History

------------

ABSOMETHING

 

Why this occurs ?

How I can get the first result ( AB__SOMETHING ) ?

 

If I do a select with the literal strings the result is as expected :

 

SELECT 'AB  ' || 'SOMETHING' AS History ;

 

History

--------------

AB  SOMETHING

 

My reasoning is wrong or this is a bug ?

 

 

"Luiz K. Matsumura" <luiz@planit.com.br> writes:
> My reasoning is wrong or this is a bug ?

This is a debatable issue.  See the thread starting here:
    http://archives.postgresql.org/pgsql-bugs/2004-07/msg00156.php
for some recent debate.  (What is not brought out in that particular
thread is that our pre-7.4 behavior was also surprising, just in
different places.  Trawling the archives for awhile may convince you
that 7.4 is better, or not.)

The bottom line in my mind is that the SQL spec's treatment of padding
space characters is very inconsistent, and so you're best off to use a
datatype that doesn't consider trailing spaces as special --- ie, use
varchar or text, and avoid char(n) like the plague.

            regards, tom lane