Sql query question - give discounts to order items using case

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SQL-Server-2005

How Can I modify the query below to give 2% discount for that line item If an order contains five or more units of a given product. AND give 5% discount for that line item If an order contains 10 or more units of a given product.

For some reason it only gives me an output for the the items that 10 or more. I need to show both discounts in the output. Thank you.

SQL

SELECT ORDERS.orderid, 
INVENTORY.partid, 
Inventory.description, 
ORDERITEMS.qty,
 Inventory.price,
 (OrderItems.qty * Inventory.price) as 'Total Original Price',

--If an order contains five or more units of a given product,  give a 2% discount for that line item. 
 (OrderItems.qty * Inventory.price * 
 CASE WHEN OrderItems.qty >= 5 THEN 0.05 ELSE 0.1 END) as 'Total Discounted Value',
 
--If an order contains ten or more units of a given product,   give a 5% discount on that line item.
(OrderItems.qty * Inventory.price * 
 CASE WHEN qty >=10 THEN 0.95/0.9 END) as 'Total Final Price of Each Product After Discount' 
 
 FROM orders, inventory, orderitems
 WHERE ORDERS.ORDERID = ORDERITEMS.ORDERID  AND ORDERITEMS.PARTID = INVENTORY.PARTID
 AND ORDERITEMS.qty >=5 AND ORDERITEMS.qty >=10

 ORDER BY ORDERS.orderid, INVENTORY.partid

Posted 19-Jan-13 10:04am

7prince

Updated 19-Jan-13 10:11am

Zoltán Zörgő

v2

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7prince 19-Jan-13 18:30pm

I adjusted it as follows: and got qty >=10 and qty >=5 orders included but this time qty >=5 orders column for 'Total Final Price of Each Product After Discount' shows NULL. What is it that I am doing wrong?

SELECT ORDERS.orderid,
INVENTORY.partid,
Inventory.description,
ORDERITEMS.qty,
Inventory.price,
(OrderItems.qty * Inventory.price) as 'Total Original Price',

--If an order contains five or more units of a given product, give a 2% discount for that line item.
(OrderItems.qty * Inventory.price *
CASE WHEN OrderItems.qty >=5 THEN 0.05 ELSE 0.1 END) as 'Total Discounted Value',

--If an order contains ten or more units of a given product, give a 5% discount on that line item.
(OrderItems.qty * Inventory.price *
CASE WHEN qty >=10 THEN 0.95/0.9 END) as 'Total Final Price of Each Product After Discount'

FROM orders, inventory, orderitems
WHERE ORDERS.ORDERID = ORDERITEMS.ORDERID AND ORDERITEMS.PARTID = INVENTORY.PARTID
AND ORDERITEMS.qty >=5
ORDER BY ORDERS.orderid, INVENTORY.partid

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Vyacheslav Voronenko · Answer 1 · 2013-01-19T10:33:00

Solution 1

1. Look on your where clause

SQL

AND ORDERITEMS.qty >=5 AND ORDERITEMS.qty >=10

This equals to just ORDERITEMS.qty >=10

2. Look on your case

SQL

CASE WHEN OrderItems.qty >= 5

you need to limit interval from right, if you want case qty>=10 to get into action

Posted 19-Jan-13 10:33am

Vyacheslav Voronenko