Porting SQL Server -> PostgreSQL ( SELECT INTO problem... )

Hi,

I'm porting an application built upon stored procedures from SQL Server to
PostgreSQL.
Most of the work was done without too many problems but now I'm testing and
I'm facing to a comportment which seems to be different.

In SQL Server, if you do :
SELECT @var1 = @var1 + col1 FROM tbl1 WHERE col2 = 1
If there is no record in tbl1 with this condition, @var1 remains unchanged.

I changed it in PostgreSQL to
SELECT INTO _var1 _var1 || col1 FROM tbl1 WHERE col2 = 1
It there is no record in tbl1 with this condition, _var1 is now NULL.

Is there an easy way to have the same result as in SQL Server or do I have
use a temporary variable and concatenate values after ?

Patrick Fiche
email : patrick.fiche@aqsacom.com
tél : 01 69 29 36 18