Function vs procedure

Compare the two routine types.

A function returns a value, a procedure does work. Function in queries, procedure via CALL.

-- function: SELECT get_tax(100);
-- procedure: CALL add_product('Kalem', 5);

Function value, procedure action.

Function vs procedure — details

A function cannot usually do INSERT/UPDATE, a procedure can. Function in queries, procedure outside.

In short: write a function when you compute a value, and a procedure when you run a sequence of steps that changes data.

Create a get_tax function and call it in a SELECT.

Show example solution

CREATE FUNCTION get_tax(price DECIMAL)
RETURNS DECIMAL
LANGUAGE SQL
AS $$
  SELECT price * 0.18;
$$;

Function

____ → returns a value

Show answer

Function → returns a value