COMPUTER APPLICATIONS 4 Marks Quetions

Distinguish between a record and a field in a table are as follows:

Record	Field
It is a collection of data items, which represent a complete unit of information about a thing or a person.	It is an area within the record reserved for a specific piece of data.
A record refers to a row in the table.	A field refers to a column in the table.
Record is also known as tuple.	Field is also known as attribute.
e.g. if Employee is a table, then entire information of an employee is called a record.	e.g. if Empolyee is a table, then empld, empName, department, salary are the fields.

Distinguish between data and information are as follows:

Data	Information
It is a raw facts.	It is a process form of data.
It considers facts symbols, images for reference or analysis.	It considers knowledge derived from study, experience or instruction.
e.g. 23 is a data.	e.g. age = 23 is information.

Steps to Design a Database
There are various steps to design a database which are as follows:

• Step 1 Determine the purpose of your database The first step of designing a database is to determine the purpose and mechanism to design and use it.
• Step 2 Determine the tables Tables are one of the most important elements of a database, consist of rows and columns. To create a well-defined database, you have to keep some conditions which are as follows:
  • A table should not contain duplicate information.
  • Each table should contain information about one subject.
    e.g. One table is used to contain the personal information of the students and the other is used to contain the marks scored by the student.
• Step 3 Determine the fields After creating a table, you need to decide the type and number of fields required for the tables in your database. Each field in a table contains individual facts about the table’s subject.
  e.g. A customer table may include company name, address, city, state and phone number fields.
• Step 4 Identify the primary key in a table From the fields of table, you need to identify a primary key which uniquely identifies each individual record of the table. The primary key helps you to reduce data duplication in the table.
• Step 5 Determine the relationship between tables In this step, you need to determine relationship between two or more tables in your database. You can set-up a relationship between tables on the basis of common field between them. Establishing a relationship allows you to fetch any information from both the tables.
• Step 6 Refine the design After you have designed the tables, fields and relationships, its time to study the design and detect any faults that might remain.
• Step 7 Enter data and create other database objects When you are satisfied that the database structure meets the goals you needed, add all your existing data to the tables.

A database consists of several components. Each component plays an important role in the database system environment.
The major components of database are as follows:

• Data
  It is raw numbers, characters or facts represented by value. Most of the organisations generate, store and process large amount of data. The data acts as a bridge between the hardware and the software. Data may be of different types such as User data, Metadata and Application Metadata.
• Software
  It is a set of programs that lies between the stored data and the users of database. It is used to control and manage the overall computerised database. It uses different types of software such as MySQL, Oracle etc.
• Hardware
  It is the physical aspect of computer, telecommunication and database, which consists of the secondary storage devices such as magnetic disks, optical discs etc., on which data is stored.
• Users
  It is the person, who needs information from the database to carry out its primary business responsibilities.

The various types of users which can access the database system are as follows:

• Database Administrator (DBA)
  A person, who is responsible for managing or establishing policies for the maintenance and handling the overall database management system is called DBA.
• Application Programmers
  The people, who write application programs in programming languages to interact and manipulate the database are called application programmers.
• End-user
  A person, who interacts with the database system to perform different operations on the database like inserting, deleting etc., through menus or forms.