PostgreSQL Function Returning Table or SETOF - sql

Question

Quick background: very new to PostgreSQL, came from SQL Server. I am working on converting stored procedures from SQL Server to PostgreSQL. I have read Postgres 9.3 documentation and looked through numerous examples and questions but still cannot find a solution.
I have this select statement that I execute weekly to return new values
select distinct id, null as charges
, generaldescription as chargedescription, amount as paidamount
from mytable
where id not in (select id from myothertable)
What can I do to turn this into a function where I can just right click and execute on a weekly basis. Eventually I will automate this using a program another developer built. So it will execute with no user involvement and send results in a spreadsheet to the user. Not sure if that last part matters to how the function is written.
This is one of my many failed attempts:
CREATE FUNCTION newids
RETURNS TABLE (id VARCHAR, charges NUMERIC
, chargedescription VARCHAR, paidamount NUMERIC) AS Results
Begin
SELECT DISTINCT id, NULL AS charges
, generaldescription AS chargedescription, amount AS paidamount
FROM mytable
WHERE id NOT IN (SELECT id FROM myothertable)
END;
$$ LANGUAGE plpgsql;
Also I am using Navicat and the error is:
function result type must be specified

Answer 1

You can use PL/pgSQL here and it may even be the better choice.
Difference between language sql and language plpgsql in PostgreSQL functions
But you need to fix a syntax error, match your dollar-quoting, add an explicit cast (NULL::numeric) and use RETURN QUERY:
CREATE FUNCTION newids_plpgsql()
RETURNS TABLE (
id varchar
, charges numeric
, chargedescription varchar
, paidamount numeric
) AS -- Results -- remove this
$func$
BEGIN
RETURN QUERY
SELECT ...;
END;
$func$ LANGUAGE plpgsql;
Or use a simple SQL function:
CREATE FUNCTION newids_sql()
RETURNS TABLE (
id varchar
, charges numeric
, chargedescription varchar
, paidamount numeric
) AS
$func$
SELECT ...;
$func$ LANGUAGE sql;
Either way, the SELECT statement can be more efficient:
SELECT DISTINCT t.id, NULL::numeric AS charges
, t.generaldescription AS chargedescription, t.amount AS paidamount
FROM mytable t
LEFT JOIN myothertable m ON m.id = t.id
WHERE m.id IS NULL;
Select rows which are not present in other table
Of course, all data types must match. I can't tell, table definition is missing.
And are you sure you need DISTINCT?