MSQL in 10 mn ~ Lesson 9 Performing Mathematical Calculations - orderitems ~ expanded_price, Sql Server

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-- https://www.safaribooksonline.com/library/view/sams-teach-yourself/9780134649160/ch09.html
-- Lesson 9 Performing Mathematical Calculations - orderitems sample #1 
CREATE TABLE orderitems
( order_num  INT       NOT NULL ,
  order_item INT       NOT NULL ,
  prod_id    NCHAR(10) NOT NULL ,
  quantity   INT       NOT NULL ,
  item_price MONEY     NOT NULL 
);
ALTER TABLE orderitems
ADD CONSTRAINT pk_orderitems PRIMARY KEY (order_num, order_item);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES
 (20005, 1, 'ANV01', 10, 5.99)
,(20005, 2, 'ANV02', 3, 9.99)
,(20005, 3, 'TNT2', 5, 10)
,(20005, 4, 'FB', 1, 10)
,(20006, 1, 'JP2000', 1, 55)
,(20007, 1, 'TNT2', 100, 10)
,(20008, 1, 'FC', 50, 2.50)
,(20009, 1, 'FB', 1, 10)
,(20009, 2, 'OL1', 1, 8.99)
,(20009, 3, 'SLING', 1, 4.49)
,(20009, 4, 'ANV03', 1, 14.99);
/*
Performing Mathematical Calculations

Another frequent use for calculated fields is performing mathematical calculations on retrieved data. 
Let’s take a look at an example.

The item_price column contains the per-unit price for each item in an order. To expand the item price 
(item price multiplied by quantity ordered), you simply do the following:
*/
SELECT 
                  prod_id
,                 quantity
,                 item_price
,                 quantity*item_price 
                  AS expanded_price
FROM 
                  orderitems
WHERE             1=1
AND               order_num = 20005
;

View schema
Execution time: 0,02 sec, rows selected: 4, rows affected: 11, absolute service time: 0,17 sec

MSQL in 10 mn ~ Lesson 9 Performing Mathematical Calculations - orderi...