It's an example that clear the concept of Normalization.

1. Normalize the following Relationupto3rd
Normal form but stepby stpe, show
each intermediateresultant table withits data.
InvoiceID InvoiceDate CusID CusName ItemID ItemName ItemQty ItemPrice InvoiceTotal
601 11/9/18 C_101 Waqas 1 Scanner 50 10$ 2500$
601 2 Mouse 100 20$
602 11/9/18 C_101 3 Printer 40 10$ 400$
603 11/9/18 C_102 Saad 2 Mouse 50 20$ 1800$
603 4 Monitor 40 10$
603 1 Scanner 40 10$
It’s unnormalized table
In order to convert into First Normal Form(1NF)
1)Must be Atomic value in each cell
2)Identify attribute or attributes that qualifies as a
Primary Key
InvoiceID InvoiceDate CusID CusName ItemID ItemName ItemQty ItemPrice InvoiceTotal
601 11/9/18 C_101 Waqas 1 Scanner 50 10$ 2500$
601 11/9/18 C_101 Waqas 2 Mouse 100 20$ 2500$
602 11/9/18 C_101 Waqas 3 Printer 40 10$ 400$
603 11/9/18 C_102 Saad 2 Mouse 50 20$ 1800$
603 11/9/18 C_102 Saad 4 Monitor 40 10$ 1800$
603 11/9/18 C_102 Saad 1 Scanner 40 10$ 1800$
Primary Key of given table consists three attributes
(InvoiceID,CusID,ItemID)
It’s a composite key
Draw lines in these attributes

2. Analysis of relationship by looking its Records(Rows)
1) One invoiceID has only one same customerID ( 601 has C_101, 602 has
C_101 and 603 has C_102). It’s one to one relationship.
2) One invoiceID has many items (601 has ItemID 1 and 2). It’s one to many
relationship.
3) One customer has many items (C_101 has itemID 1,2 and 3). It’s one to
many relationship.
In order to convert into second Normal Form(2NF)
1)It’s in 1NF
2) No partial dependency
Partial Dependency: Non-key attributes depend on
a part of Primary key.
Non-Key attribute: The atttibute or set of attributes
that cannot be qualified as a Primarykey (Which can
not be used to identify a record uniquely.
Here, InvoiceID,CusID and ItemID is a part of
primary key.

3. List out Non-key attributes: InvoiceDate,
InvoiceTotal, CusName, ItemName, ItemQty and
ItemPrice
InvoiceDate and InvoiceTotal are depend
on a part of primary key (InvoiceID). It
must be fully dependent on InvoiceID (not
a part of primary key).
CusName is dependent on a part of primary
key (CusID). It must be fully dependent on
CusID (not a part of primary key).
ItemName, ItemQty and ItemPrice are
dependent on a part of primary key (ItemID). It
must be fully dependent on ItemID (not a part
of primary key).
InvoiceID InvoiceDate InvoiceTotal
601 11/9/18 2500$
602 11/9/18 400$
603 11/9/18 1800$
Invoice
Now InvoiceDate and InvoiceTotal are dependent onprimary key.
CusID CusName
C_101 Waqas
C_102 Saad
Customer

4. Now CusName is dependent on primary key.
It’s incorrect relation(Table). How??????
ItemID ItemName ItemQty ItemPrice
1 Scanner 50 10$
2 Mouse 100 20$
3 Printer 40 10$
4 Monitor 40 10$
Oh!!!!!!!! NO
Are you noticed that we have lost some data?
=>Let check it, in 1NF relation
ItemID 1 has ItemQty 50 of CusID C_101
And ItemID 1 has ItemQty 40 of CusID C_102.
In this way, we have lost record of CusID C_102 about its
itemQty 40.
ItemID ItemName ItemPrice
1 Scanner 10$
2 Mouse 20$
3 Printer 10$
4 Monitor 10$
Item
CusID ItemID ItemQty
C_101 1 50
C_101 2 100
C_101 3 40
C_102 2 50

5. C_102 4 40
C_102 1 40
Customer_Item
Customer_Itemis satisfied the relationship3.
InvoiceID ItemID
601 1
601 2
602 3
603 2
603 4
603 1
Invoice_Item
Invoice_Itemis satisfiedrelationship2.
We have done our relationshipsdata analysis
All relations(Tables)Customer, Item, Invoice,
Invoice_Item and Customer_Item are in 2NF.
Now, we are moving to convert into third Normal
Form(3NF).
1) It’s in 2NF
2) No transitive dependency
Transitive Dependency: Non key attributes depend on
another non-key attributes.

6. All these relationare in3NF.
Because there is not exist any transitive dependency.