Question

What are normal forms ? explain varoius normal form ?

Answer 1

Database Management System Design

As you know, a database is a collection of information or data organized and stored in tables with efforts made to ensure its accuracy and ease of retrieval.

During the design process on a DBMS, it is of utmost importance that the arrangement of tables and their relation to each other is correct, and how data is added, edited and deleted is taken into consideration. The table structures, consisting of columns and rows, is also important.

The Normal Forms

Certain rules in DBMS have been developed to better organize tables and minimize anomalies. The stage at which a table is organized is known as its normal form (a stage of normalization). There are three types/stages of normal forms are known as First Normal Form (1NF), Second Normal Form (2NF) and Third Normal Form (3NF). As a table progressively satisfies the conditions of the different normal forms, it is less prone to the anomalies discussed earlier.

Types of Normal FormsFirst Normal Form (1NF)

A table is said to be in 1NF if the following rules hold:

Columns must have single valuesColumns must have unique namesValues of a given attribute must be of the same data typeNo two records (rows) can be identical.

Let's assume you're the new hairdresser in town. You want to store the names and contact details of clients in a database. Your trainee staff creates the following table:

ClientIDClientNameClientNo015John256-2568, 524-4589016Princess487-5485,451-copy027Tom458-4587028Claire478-2689, 265-1486029Robert485-5584, 254-visa

Look closely and you'll see that the table does not conform to the rules of 1NF. The reason for this is:

That the trainee staff saved the second mobile numbers of John Princess and Robert within the same field which violates Rule 1.The second entries for Princess and Robert are stored in wrong data format. All other number are saved in number format (numbers only) while their second numbers are stored as strings (numbers and letters). This violates rule 3.

ClientIDClientNameClientNo015John256-2568015John524-4589016Princess487-5485016Princess451-2679027Tom458-4587028Claire478-2689028Claire265-1486029Robert485-5584029Robert254-8472

Answer 2

Answer:

in an adiabatic process no exchange of energy between system and surrounding takes place.