function pl sql with select

1CREATE FUNCTION function_name … RETURN BOOLEAN IS
2	Definitions;
3BEGIN
4	Statement;
5	RETURN "Hello World!";
6END;

1   CREATE OR REPLACE FUNCTION get_total_sales(
2    in_year PLS_INTEGER
3) 
4RETURN NUMBER
5IS
6    l_total_sales NUMBER := 0;
7BEGIN
8    -- get total sales
9    SELECT SUM(unit_price * quantity)
10    INTO l_total_sales
11    FROM order_items
12    INNER JOIN orders USING (order_id)
13    WHERE status = 'Shipped'
14    GROUP BY EXTRACT(YEAR FROM order_date)
15    HAVING EXTRACT(YEAR FROM order_date) = in_year;
16    
17    -- return the total sales
18    RETURN l_total_sales;
19END;