What is a View in SQL Server?

A view in SQL Server is a virtual table that is based on the result set of a SQL query. It does not store the data itself but provides a way to present data from one or more tables in a specific format. Views can simplify complex queries, enhance security by restricting access to specific data, and provide a layer of abstraction over the underlying tables.

Key Characteristics of Views

1. Virtual Table: A view behaves like a table but does not store data physically. It retrieves data from the underlying tables when queried.
2. Simplification: Views can encapsulate complex queries, making it easier for users to access data without needing to understand the underlying table structures.
3. Security: Views can restrict access to specific columns or rows in a table, allowing users to see only the data they are permitted to view.
4. Updatable Views: Some views can be updated, allowing users to modify the underlying data through the view, provided certain conditions are met.

How to Create a View

The basic syntax for creating a view is as follows:

sql
1CREATE VIEW view_name AS
2SELECT column1, column2, ...
3FROM table_name
4WHERE condition;

Example of Creating a View

Let's say we have a table named Employees:

sql
1CREATE TABLE Employees (
2    EmployeeID INT PRIMARY KEY,
3    FirstName VARCHAR(50),
4    LastName VARCHAR(50),
5    Department VARCHAR(50),
6    Salary DECIMAL(10, 2)
7);

Step 1: Insert Sample Data

sql
1INSERT INTO Employees (EmployeeID, FirstName, LastName, Department, Salary)
2VALUES 
3(1, 'John', 'Doe', 'HR', 60000),
4(2, 'Jane', 'Smith', 'IT', 75000),
5(3, 'Sam', 'Brown', 'Finance', 70000),
6(4, 'Lisa', 'White', 'IT', 80000);

Step 2: Create a View

Now, let's create a view that shows only the employees in the IT department along with their salaries:

sql
1CREATE VIEW ITEmployees AS
2SELECT EmployeeID, FirstName, LastName, Salary
3FROM Employees
4WHERE Department = 'IT';

How to Use the View

You can query the view just like a regular table:

sql
1SELECT * FROM ITEmployees;

Expected Output :