Database Systems
Lecture # 16
Chapter # 10
Normalization
Second Normal Form (2NF)
• A relation that is in 1NF and every non-primary-key
attribute is fully functionally dependent on the
primary key.
• In other words
– A table that is in 1NF and in which the values of
each non-primary-key column can be worked out
from the values in all the columns that make up
the primary key is said to be in 2NF.
2
2NF
• Identify the primary key for the 1NF relation.
• Identify the functional dependencies in the relation.
• If partial dependencies exist on the primary key
remove them by placing then in a new relation along
with a copy of their determinant (Primary Key).
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Example 1: TempStaffAllocation table
is in 2NF
2NF
: A relation that is in 1NF and every nonprimary-key attribute is fully functionally
dependent on the primary key.
Is
table in 1NF (Yes)
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Example 1: TempStaffAllocation table
is not in 2NF
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Example 1: Converting TempStaffAllocation table to 2NF
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Example(2) 2NF
• EmpNo
• ProNo
• Hours
•
•
•
•
EmpName
ProName
ProLocation
Is table in 2NF ?
: Employee Number (PK).
: Project Number (PK).
: Number of Work
Hours in the project.
: Employee Name.
: Project Name.
: Project Location.
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Example(2) 2NF
10.3
EmployeePrject (Is table in 1NF) (YES)
EmpNo
ProNo Hours EmpName ProName ProLocation
EmployeePrject (Is table in 2NF)
EmpNo
ProNo Hours EmpName ProName ProLocation
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Example(2) 2NF
Emp_proj1 (2NF)
EmpNo ProNo
Hours
Emp_proj2 (2NF)
EmpNo
EmpName
Emp_proj3 (2NF)
ProNo
ProName
ProLocation
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Example(3) 2NF
•
•
•
•
SNo
CNo
SName
CName
: Student Number (PK).
: Course Number (PK).
: Student Name.
: Course Name.
• Is table in 2NF ?
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Example(3) 2NF
Student (Yes, Student table in 1NF)
SNo
CNo
SName
CName
Student (Is Student table in 2NF)
SNo
CNo
SName
CName
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Example(3) 2NF
Student (2NF)
SNo
SName
Course (2NF)
CNo
CName
Sts_Crs (2NF)
SNO
CNO
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Third Normal Form (3NF)
• A relation that is in 1NF and 2NF and in which
no non-primary-key attribute is transitively
dependent on the primary key.
• In other words
– A table that is in 1NF and 2NF and in which
all non-primary-key columns can be worked
out from only the primary key column(s) and
no other columns.
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2NF to 3NF
• Identify the primary key in the 2NF relation.
• Identify functional dependencies in the relation.
• If transitive dependencies exist on the primary key
remove them by placing them in a new relation along
with a copy of their dominant.
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Example 3-1 :StaffBranch table is in 3NF
A relation
that is in 1NF and 2NF and in which no nonprimary-key attribute is transitively dependent on the primary
key.
Is
table in 1NF (Yes)
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Example 3-1 :StaffBranch table is in 3NF
Is
table in 2NF (Yes)
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Example 3-1 : StaffBranch table is not in 3NF
2NF
3NF
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Example 3-1 : Converting the StaffBranch table to 3NF
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Example(3-2) 3NF
•
•
•
•
•
•
EmpNo
EmpName
BDate
Address
DNo
DName
: Employee Number (PK).
: Employee Name.
: Birth Date.
: Address
: Department Number.
: Department Name.
• Is table in 3NF ?
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Example(3-2) 3NF
Employee (Is Employee table in 1NF) (YES)
EmpNo
EmpName
BDate
Address
DNo
DName
Employee (Is Employee table in 2NF) (YES)
EmpNo
EmpName
BDate
Address
DNo
DName
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Example(3-2) 3NF
Employee (Is Employee table in 3NF)
EmpNo
EmpName
BDate
Address
DNo
DNam
e
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Example(3-2) 3NF
Employee in 3NF
EmpNo EmpName BDate Addres DNo
s
Department in 3NF
DNo
DName
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Example(3-3) 3NF
•
•
•
•
CNo
CName
InsNo
InsOff
: Course Number (PK).
: Course Name.
: Instructor Number.
: Instructor Office.
• Is table in 3NF ?
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Example(3-3) 3NF
Student (YES table in 1NF)
CNo
CName
InsNo
InsOff
Student (Is table in 2NF) (YES)
CNo
CName
InsNo
InsOff
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Example(3-3) 3NF
Student (Is table in 3NF)
CNo
CName
InsNo
InsOff
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Example(3-3) 3NF
Student (3NF)
CNo
CName
InsNo
Instractor (3NF)
InsNo
InsOff
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