DROP PROCEDURE IF EXISTS prc_inv_amounts;
CREATE PROCEDURE prc_inv_amounts(IN INV_NUM INT)
BEGIN
DECLARE SUBTOTAL INT DEFAUL T0;
DECLARE TAX FLOAT DEFAULT 0;
SELECT SUM(LINE_TOTAL)
INTO SUBTOTAL
FROM LINE
WHERE INV_NUMBER = INV_NUM;
SET TAX = 0.8*SUBTOTAL;
UPDATE INVOICE
SET INV_SUBTOTAL = SUBTOTAL
, INV_TAX = TAX
, INV_TOTAL = SUBTOTAL+TAX
WHERE INV_NUMBER = INV_NUM;
END;