Answer:
The procedure in SQL is created as follows
Explanation:
--creating the procedure
CREATE OR REPLACE PROCEDURE prc_inv_amounts (W_IN IN NUMBER)
AS
--defining variables
W_CK NUMBER := 0;
W_SUBT NUMBER := 0;
W_TAX NUMBER := 0;
BEGIN
--Authentication process of the invoice
SELECT COUNT(*) INTO W_CK FROM INVOICE WHERE INV_NUMBER := W_IN;
--Transaction confirmation
IF W_CK = 1 THEN
SELECT SUM(LINE_TOTAL) INTO W_SUBT FROM LINE
WHERE
--checking the invoice for the desired invoice number
LINE.INV_NUMBER = W_IN;
W_TAX :=W_SUBT * 0.08;
--updating the invoice
UPDATE INVOICE
--setting the new values
SET INV_SUBTOTAL = W_SUBT,
INV_TAX = W_TAX,
INV_TOTAL =W_SUBT + W_TAX
WHERE INV_NUMBER = W_IN;
--ending the if statement
END IF;
--ending the procedure
END;