Question

I cannot seem to find a way to pass my query as a parameter to my sql-function. My problem is table ‘my_employees1’ could be dynamic.

DROP FUNCTION function_test(text);
CREATE OR REPLACE FUNCTION function_test(text) RETURNS bigint AS '
    DECLARE ret bigint;
    BEGIN 
        SELECT count(mt.id) INTO ret
    FROM mytable as mt
    WHERE mt.location_id = 29671
    --and mt.employee_id in (SELECT id from my_employees1);
    --and mt.employee_id in ($1);
    $1;
    RETURN ret;
    END;
' LANGUAGE plpgsql;

select function_test('and mt.employee_id in (SELECT id from my_employees1)');
select function_test('SELECT id from my_employees1');

Answer 1

It must be dynamically built:

DROP FUNCTION function_test(text);
CREATE OR REPLACE FUNCTION function_test(text) RETURNS bigint AS $$
    DECLARE
        ret bigint;
    BEGIN
    execute(format($q$
        SELECT count(mt.id) INTO ret
        FROM mytable as mt
        WHERE mt.location_id = 29671
        %s; $q$, $1)
    );
    RETURN ret;
    END;
$$ LANGUAGE plpgsql;

The $$ and $q$ are dollar quotes. They can be nested as long as the inner identifier is different. In addition to the obvious advantages of permitting the use of unquoted quotes and being nestable it also let the syntax highlighting do its work.