Bug #604: string join problem

Erol Ozcan (erol(at)infotron(dot)com(dot)tr) reports a bug with a severity of 2
The lower the number the more severe it is.

Short Description
string join problem

Long Description
I have a major problem with string joining in sql query in Postgresql 7.1.3. It is always return null string if any of column has null value.
I attached some example code sources to explain the problem.

Sample Code
CREATE TABLE phone
(
phn_id INT NOT NULL PRIMARY KEY,
phn_country INT NULL,
phn_area INT NULL,
phn_number INT NULL,
phn_ext INT NULL
);
INSERT INTO phone VALUES( 30, 90, 216, 4921002, NULL );
SELECT '+'|| phn_country||'-'||phn_area||'-'||phn_number FROM phone WHERE phn_id=30;
?column?
-----------------
+90-216-4921002
(1 row)

SELECT '+'||phn_country||'-'||phn_area||'-'||phn_number||' ext:'||phn_ext FROM phone WHERE phn_id=30;
?column?
----------

(1 row)

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