Обсуждение: Problem with function returning a result set

Hi,

I'm playing around with functions returning result sets, and I have a problem with the following function:

-- Create sample data
CREATE TABLE employee (id integer, first_name varchar(50), last_name varchar(50));
INSERT INTO employee values (1, 'Arthur', 'Dent');
INSERT INTO employee values (2, 'Zaphod', 'Beeblebrox');
INSERT INTO employee values (3, 'Ford', 'Prefect');
COMMIT;

-- Create the function
CREATE OR REPLACE FUNCTION get_employees(name_pattern varchar)
RETURNS TABLE(id integer, full_name text)
AS
$$
BEGIN
  RETURN QUERY    SELECT id, first_name||' '||last_name    FROM employee    WHERE last_name LIKE name_pattern ||'%';
END
$$
LANGUAGE plpgsql;

COMMIT;

Now when I run:

SELECT *
FROM get_employees('D');

I get one row returned which is correct, but the ID column is null (but should be 1). It does not depend which row(s) I
selectthrough the procedure. I also tried to change the datatype of the returned id to int8 and an explicit cast in the
SELECTstatement, but to no avail.
 

When I define the function using SQL as a language (with the approriate changes), the ID column is returned correctly.

I'm using Postgres 8.4.3 on Windows XP
postgres=> select version();                           version
------------------------------------------------------------- PostgreSQL 8.4.3, compiled by Visual C++ build 1400,
32-bit
(1 row)

What am I missing?

Regards
Thomas

Thomas Kellerer <spam_eater@gmx.net> writes:
> CREATE OR REPLACE FUNCTION get_employees(name_pattern varchar)
> RETURNS TABLE(id integer, full_name text)
> AS
> $$
> BEGIN

>    RETURN QUERY
>      SELECT id, first_name||' '||last_name
>      FROM employee
>      WHERE last_name LIKE name_pattern ||'%';
> END
> $$
> LANGUAGE plpgsql;

> I get one row returned which is correct, but the ID column is null
> (but should be 1).

Don't name the parameter the same as the table column ...
        regards, tom lane

2010/4/8 Thomas Kellerer <spam_eater@gmx.net>:
> Hi,
>
> I'm playing around with functions returning result sets, and I have a
> problem with the following function:
>
> -- Create sample data
> CREATE TABLE employee (id integer, first_name varchar(50), last_name
> varchar(50));
> INSERT INTO employee values (1, 'Arthur', 'Dent');
> INSERT INTO employee values (2, 'Zaphod', 'Beeblebrox');
> INSERT INTO employee values (3, 'Ford', 'Prefect');
> COMMIT;
>
> -- Create the function
> CREATE OR REPLACE FUNCTION get_employees(name_pattern varchar)
> RETURNS TABLE(id integer, full_name text)
> AS
> $$
> BEGIN
>
>  RETURN QUERY
>    SELECT id, first_name||' '||last_name
>    FROM employee
>    WHERE last_name LIKE name_pattern ||'%';
> END
> $$
> LANGUAGE plpgsql;
>
> COMMIT;
>
> Now when I run:
>
> SELECT *
> FROM get_employees('D');
>
> I get one row returned which is correct, but the ID column is null (but
> should be 1). It does not depend which row(s) I select through the
> procedure. I also tried to change the datatype of the returned id to int8
> and an explicit cast in the SELECT statement, but to no avail.
>
> When I define the function using SQL as a language (with the approriate
> changes), the ID column is returned correctly.
>
> I'm using Postgres 8.4.3 on Windows XP
> postgres=> select version();
>                           version
> -------------------------------------------------------------
>  PostgreSQL 8.4.3, compiled by Visual C++ build 1400, 32-bit
> (1 row)
>
> What am I missing?

there are collision between SQL and PLpgSQL identifiers.
RETURNS TABLE(id integer, full_name text) AS$$BEGIN RETURN QUERY   SELECT e.id, e.first_name||' '||e.last_name   FROM
employeee   WHERE e.last_name LIKE e.name_pattern ||'%';END$$LANGUAGE plpgsql; 

use aliases.

Regards
Pavel Stehule

>
> Regards
> Thomas
>
>
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Tom Lane, 08.04.2010 10:59:
> Thomas Kellerer<spam_eater@gmx.net>  writes:
>> CREATE OR REPLACE FUNCTION get_employees(name_pattern varchar)
>> RETURNS TABLE(id integer, full_name text)
>> AS
>> $$
>> BEGIN
>
>>     RETURN QUERY
>>       SELECT id, first_name||' '||last_name
>>       FROM employee
>>       WHERE last_name LIKE name_pattern ||'%';
>> END
>> $$
>> LANGUAGE plpgsql;
>
>> I get one row returned which is correct, but the ID column is null
>> (but should be 1).
>
> Don't name the parameter the same as the table column ...
>
>             regards, tom lane
>
I knew it was something simple I overlooked ;)

Thanks for the quick response.

Regards
Thomas