Normal Form III

Back to: DATA PROCESSING SS 2

 

Welcome to class! 

In today’s class, we will be talking more about normal form. Enjoy the class!

Normal Form III

Key

A key is an attribute or field that can be used to identify a record in a database table or file.

The primary key is a unique attribute that can be used to identify a record in a database table. For Example, in the student database table above, the attribute that is unique to identify each record is the Student-ID or RegNo.

Concepts of foreign key

A foreign key is a field in a relational table that matches a candidate key of another table. A foreign key (FK) is a column or combination of columns that are used to establish and enforce a link between the data in two tables. You can create a foreign key by defining a FOREIGN KEY constraint when you create or modify a table. The foreign key can be used to cross-reference table. The foreign key identifies a column or set of columns in one (referencing or child) table that refers to a column or set of columns in another (referenced or parent) table. The columns in the child table must reference the columns of the primary key or other super keys in the parent table.

Explain the determination of Normal Form

Normalization is a technique for producing a set of suitable relations that support the data requirements of an enterprise. Characteristics of a suitable set of relations include:

1. The minimal number of attributes necessary to support the data requirements of the enterprise
2. Attributes with a close logical relationship are found in the same relation.
3. Minimal redundancy with each attribute represented only once with the important exception of attributes that form all or part of foreign keys.

General evaluation

1. Define Key as regards to the database.
2. Differentiate between primary key and foreign key

Weekend assignment

1. Using tables, explain the differences between primary key and foreign key.
2. State two characteristics of suitable relations that support the data requirements of an enterprise.

 

In our next class, we will be talking about Entity–Relationship Models.  We hope you enjoyed the class.

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