CREATE OR REPLACE PROCEDURE change_credit
   (p_in_id   IN   customers.customer_id%TYPE, 
    o_credit OUT NUMBER)
   IS
   BEGIN
    UPDATE customers
    SET    credit_limit = credit_limit * 1.10 
    WHERE  customer_id = p_in_id
    RETURNING credit_limit INTO o_credit;
END change_credit;
/
VARIABLE g_credit NUMBER
EXECUTE change_credit(109, :g_credit)
PRINT g_credit
