Chapter 5, Problem 5.1RQ

Explain how entities are transformed into tables.

Explanation of Solution

Entity:

An entity is an object that the user wants to model and store the information about an object.

• Entity normally recognizable concepts such as things, place, person, unit or any item relevance to the database.
• Employee, Lecturer, Student are some of the examples of entities.

Table:

Table is a collection of associated data, consists of rows and columns.

• These data are arranged in a structured layout within a database.

Steps for transforming entities into table:

• In the start a table for each entity is created and the name is given to that entity.
• Specify the primary key for that table.
• Columns has to created in relation for each and every attribute present in the entity.
• In the final step, normalize the table.

Example:

Consider the example of transforming entity into table is as follows:

Entity:

Table:

Explanation:

In the above entity diagram, the “Student” is the entity and “number”, “name”, “age”, “sex”, and “course” are the attributes of that entity.

In the above table, “number” acts as the primary key for the “Student” table. Finally normalize the data in the table.