How to condition on a list of parameters in PGSQL - postgresql

Question

I'm looking to input a list of integers into a function and return rows based on this. In this case, I want to select some attributes based on employer id, e.g. select where employer id = 102,103 and 105.
This is what I have tried.
CREATE OR REPLACE FUNCTION dummy(VARIADIC e_id NUMERIC[])
RETURNS TABLE (
emp_id INT,
first_name VARCHAR,
last_name VARCHAR,
salary INT
)
AS $$
BEGIN
RETURN QUERY SELECT em.emp_id, em.first_name, em.last_name, em.salary
FROM employee em
WHERE em.emp_id IN e_id;
END; $$
LANGUAGE PLPGSQL;
SELECT *
FROM dummy(102, 103, 105);
The error appears to be from the line containing WHERE. How am I able to select based on the list of integers e_id?

Answer 1

WHERE em.emp_id IN e_id
Since you are dealing with a list of numbers, you could just use the any construct instead of in:
CREATE OR REPLACE FUNCTION dummy(VARIADIC e_id NUMERIC[])
RETURNS TABLE (
emp_id INT,
first_name VARCHAR,
last_name VARCHAR,
salary INT
)
AS $$
BEGIN
RETURN QUERY SELECT em.emp_id, em.first_name, em.last_name, em.salary
FROM employee em
WHERE em.emp_id = any (e_id);
END; $$
LANGUAGE PLPGSQL;
Demo on DB Fiddle
create table employee(emp_id int, first_name varchar(50), last_name varchar(50), salary int);
insert into employee values
(1, 'a', 'b', 50),
(2, 'c', 'd', 100),
(3, 'e', 'f', 400);
CREATE OR REPLACE FUNCTION dummy(VARIADIC e_id NUMERIC[])
RETURNS TABLE (
emp_id INT,
first_name VARCHAR,
last_name VARCHAR,
salary INT
)
AS $$
BEGIN
RETURN QUERY SELECT em.emp_id, em.first_name, em.last_name, em.salary
FROM employee em
WHERE em.emp_id = any (e_id);
END; $$
LANGUAGE PLPGSQL;
SELECT * FROM dummy(1, 2);
emp_id | first_name | last_name | salary
-----: | :--------- | :-------- | -----:
1 | a | b | 50
2 | c | d | 100