View Level in DBMS: Definition, Example, and Usage

In a DBMS, the view level refers to the way users see the database, focusing on how data is presented rather than how it is stored. It is the highest level of abstraction that hides the complexity of the physical storage and internal structure from users.

How It Works

The view level in a database management system is like looking at a map instead of the actual terrain. It shows only the parts you need to see, hiding all the complex details underneath. This level provides a simplified and customized way for users to interact with the data without worrying about how it is stored or organized internally.

Think of it as a restaurant menu. You see the dishes (data) and their descriptions (structure), but you don't see the kitchen, ingredients, or cooking process (physical storage). The view level lets different users see different parts of the database tailored to their needs, improving security and ease of use.

Example

This example shows how a view can be created in SQL to present specific data from a table, hiding other details.

sql

CREATE TABLE Employees (
  EmployeeID INT,
  Name VARCHAR(50),
  Department VARCHAR(50),
  Salary INT
);

INSERT INTO Employees VALUES
(1, 'Alice', 'HR', 5000),
(2, 'Bob', 'IT', 6000),
(3, 'Charlie', 'IT', 5500);

CREATE VIEW IT_Employees AS
SELECT Name, Department FROM Employees WHERE Department = 'IT';

SELECT * FROM IT_Employees;

Output

Name    | Department
--------|-----------
Bob     | IT
Charlie | IT

When to Use

Use the view level when you want to simplify data access for users or applications. It helps in hiding sensitive information like salaries or personal details while still allowing users to work with relevant data.

For example, a manager might only need to see employee names and departments, not their salaries. Views also help in maintaining security, reducing complexity, and providing a consistent interface even if the underlying database changes.

Key Points

• View level is the highest abstraction in DBMS, showing data as users need it.
• It hides physical storage and internal database details.
• Views can restrict access to sensitive data.
• It simplifies user interaction with the database.
• Views can be customized for different user needs.

Key Takeaways

View level hides database complexity and shows only relevant data to users.

It improves security by restricting access to sensitive information.

Views provide a simplified and customized interface for different users.

Using views helps maintain consistency even if the database structure changes.