What is a function?

Learn routines that return a scalar value.

A function is SQL code that returns a value. Called inside a query.

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

Function that computes tax.

The function get_tax is created. The expression price * 0.18 is evaluated and returned.

What is a function? — details

A function returns a value; a procedure does work. A function is used inside queries.

For example, get_tax(price) computes the tax for each row and is used like a column in SELECT name, get_tax(price) FROM products.

Create a get_tax function: return 18% of the price.

Show example solution

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

Add RETURNS

CREATE FUNCTION get_tax(price DECIMAL)
____ DECIMAL

Show answer

CREATE FUNCTION get_tax(price DECIMAL)
RETURNS DECIMAL