Elementary Data Organization

In this article, we'll take a look about all the basic terms used in data structure. These terms are the building blocks of data structure.

1. Data

Data can be defined as a representation of facts, concepts or instructions in a formalized manner suitable for communication, interpretation or processing by human or electric machines. Data is represented with the help of characters like alphabets (A-Z,a-z), digits (0-9) and special characters (+,-,*,<, >, =, ^ etc.).

2. Data Item (Field)

A set of characters which are used together to represent a specific data element e.g. name of a student in a class is represented by the data item, say NAME.
The data items can be classified into two types depending on the usage:

1. Elementary Data Items: These data items can’t be further sub-divided. For e.g. ROLL NUMBER.
2. Group Data Items: These data items can be further sub-divided into elementary data items. For example: DATE may be divided into Days, Months and Years.

3. Record

Record is a collection of related data items. E.g. a student record for a student’s contains data fields such as name, age, sex, class etc.

4. File (Data File)

File is collection of logically related records. E.g. a payroll file might consist of the employee pay records for a company.

5. Entity:

An entity is a person, place, thing, event or concept about which information recorded.

6. Attribute:

Attributes gives the characteristics or properties of the entity.

7. Data Value:

A data value is the actual data or information contained in each attribute.

Example:

• Entity : Employee
• Attributes: Id, Name, Age
• Value: 1, ABC, 18

8.Entity Set

Entities with similar attributes form an entity set. For example, All the employees in an organization form an entity set.

9. Primary and Secondary Keys:

Primary Key: A field or collection of fields in a record which identifies a record uniquely is called a primary key or simply key. In a student file: ID is primary key.
Secondary Key: A field in a record which identifies the records but not uniquely is called a secondary key. For Example, NAME and MARKS are the secondary keys in Student file.