Lesson Notes By Weeks and Term - Senior Secondary 2

Normal form III

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Term: 1st Term

Week: 8

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 2 periods each

Date:       

Subject:      Data Processing

Topic:-       Normal Form III

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Define normal forms
  2. State the goals of normalization

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, pictures, Data Processing for senior Secondary Education by Hiit Plc, WAPB Computer Studies for Senior Secondary I by Adekunle et al, On-line Materials.

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S ACTIVITY

STEP 1

INTRODUCTION

The teacher reviews the previous lesson on Normalization

Students pay attention

STEP 2

EXPLANATION

He explains the meaning of normal forms and list all the types of normal forms

 

Students pay attention and participates

STEP 3

DEMONSTRATION

He explains the first normal forms; how to create and covert tables into first normal form and the problems associated with it

Students pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a summarized note on the board

The students copy the note in their books

 

NOTE

Second normal form (2NF)

A database table is in a 2NF if and only if:

  1. It is in 1NF and
  2. Every non-key attribute is fully functionally dependent on the primary key i.e. there should be no partial dependency in the table

Table 2

Consider the Table 2 above, the non-key attributes

are colour, price and tax. The attribute item is the primary key. The price

and the tax are functionally dependent on the item and not on the colour i.e.

the item determines the price and not the colour.

 

So what do you do to normalize into 2NF?

Decompose the 1NF table and set up a new relation (table) for each partial

key with its dependent attributes. Make sure to keep a table with the original

primary key and any attributes that are fully functionally dependent on it.

 

Having decomposed the above table, the tables below are now in 2NF

 

Third normal form (3NF)

The third normal form's objective is to remove data in a table that is not

dependent on the primary key.

A database table is said to be in 3NF if:

  • It is in a 2NF
  • All non-key field depend only on the primary key – no transitive dependency (i.e. Eliminate all fields that do not depend on the primary key by moving them into a separate table)

 

Tables 2NF(b) is not in third normal form because Tax depends on price,

not item.

To normalize to 3NF, decompose the table and set up a new table that

includes the non-key attribute(s) i.e. price, that functionally determine(s)

other non-key attribute(s) i.e. tax

 

The tables below are now in 3NF.

 

EVALUATION:    1. Define the second and the third normal forms

  1. How can a first normal form e normalized into a second normal form?
  2. How can a second normal form be normalized to a third normal form?

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively