For your project: (a) Show all the relations before normalization. (b) Show all
ID: 3824138 • Letter: F
Question
For your project: (a) Show all the relations before normalization. (b) Show all the relations in INF. (c) List all the partial functional dependencies for each relation. (d) Bring all the relations in 2NF. (e) List all the transitive dependencies for each relation. If) Bring all the relations In 3NF. Normal form A stale of a relation that results from applying simple rules regarding functional dependence (or relationships between attributes) to that relation. INF is data in first normal form. In order to show a relation in INF, repeating groups must be removed. That is, you cannot have two values in one cell of a table. Study textbook pages 181 onwards.Explanation / Answer
1NF:
As per First Normal Form, no two Rows of data must contain repeating group of information Let us consider below example.
Student table
Student
Age
Subject
Adam
15
Biology, Maths
Alex
14
Maths
Stuart
17
Maths
For the above table it is not in 1NF. Because it contains duplicate values.
Student
Age
Subject
Adam
15
Biology
Adam
15
Maths
Alex
14
Maths
Stuart
17
Maths
data redundancy increases by using 1Nf.
2NF:
As per the Second Normal Form there must not be any partial dependency of any column on primary key.
By considering above table, partial dependencis are:
Age--à Subject. We have to avoid partial dependencies.
Student
Age
Adam
15
Alex
14
Stuart
17
Here {student, Age} Here Student is primary key
Student
Subject
Adam
Biology
Adam
Maths
Alex
Maths
Stuart
Maths
. Here {student, Subject} Here Student is primary key.
3NF:
As per 3NF Third Normal form every non-prime attribute of table must be dependent on primary key.
And should be in 2nd normal form.
Let us consider this example.
Student_Detail Table :
Student_id
Student_name
DOB
Street
city
State
Zip
As per this,
Here Student_id is Primary key, but street, city and state depends upon Zip. This type of relationship is called transitive dependancy. Hence to apply 3NF, we need to move the street, city and state to new table, with Zip as primary key.
New Student_Detail Table :
Student_id
Student_name
DOB
Zip
Address Table :
Zip
Street
city
state
Student
Age
Subject
Adam
15
Biology, Maths
Alex
14
Maths
Stuart
17
Maths
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