Double-Checking Normalization Results

It's a good practice to double-check your normalization by attempting two verifications. The first is to do a data verification.

Data Verification

Note: This "verification" section would not be required on a lab. It's here for demonstration purposes only, as a step you would do on your own to see if the data "fits" your final set of normalized entitied.

The verification of the final set of entities after going through the normalization process can be demonstrated by drawing tables with the original document's data entered as a sample.

Order Table

OrderNumber	CustomerNumber	Date	Subtotal	GST	Total
219	137	Jan 16, 2000	24.29	1.70	25.99

Customer Table

CustomerNumber	FirstName	LastName	Address	City	Province	PostalCode	HomePhone
137	Fred	Smith	123 SomeWhere St.	Edmonton	AB	T5H 2J9	436-7867

OrderDetail Table

OrderNumber	ItemNumber	Quantity	SellingPrice	Amount
219	H23	1	11.99	11.99
219	H319	2	4.99	9.98
219	M24	8	0.29	2.32

Item Table

ItemNumber	Description	CurrentPrice†
H23	Heater Fan Belt - 23"	11.99
H319	Heater Fan Belt Support Brackets	4.99
M24	Bolts - 24 mm	0.29

^† - The current price for items can change over time.

ERD Description

Note: This "ERD Description" section would not be required on a lab. It's here for demonstration purposes only, as a step you would do on your own to see if the structure/relationships make sense among your final set of normalized entitied.

• Each Customer must be one who places one or more Orders.
• Each Order must be placed by one and only one Customer.
• Each Order must be made up of one or more OrderDetails.
• Each OrderDetail must be for one and only one Order.
• Each Item may be sold under one or more OrderDetails.
• Each OrderDetail must be a sale of one and only one Item.