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What is a VIEW in SQL?

Parthiban Kannan
Updated on December 2, 2025

1 min read

A VIEW in SQL is essentially a virtual table — it does not store data physically, but instead displays data from one or more tables based on a query. You can think of it as a saved SELECT statement that can be treated like a table in other queries.

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filename.sql 
CREATE VIEW employee_summary AS
SELECT department, COUNT(*) AS num_employees, SUM(salary) AS total_salary
FROM employees
GROUP BY department;

Here, employee_summary is a view that shows the number of employees and total salary per department.

Using a View: #

Once created, you can query it like a regular table:

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filename.sql 
SELECT * FROM employee_summary
WHERE total_salary > 50000;

Real-world scenario: #

I used views to simplify reporting in a sales project. Instead of writing a complex JOIN and aggregation query every time for top-performing products, I created a view that combined orders, products, and customers tables with all necessary calculations. This made reporting queries cleaner, easier, and less error-prone.

Advantages of Views: #

  • Simplifies complex queries for end users.
  • Enhances security — you can grant access to a view without exposing the underlying tables.
  • Encapsulates business logic — calculations or joins can be hidden inside the view.

Challenges: #

  • Some views, especially those with multiple joins or aggregations, can be slow on large datasets.
  • Updating data through a view can be limited if it involves multiple tables or aggregations.

Limitations: #

  • Standard views are read-only if they contain joins, aggregations, or DISTINCT, depending on the database.
  • Views do not store data physically, so complex views are computed on-the-fly, which can affect performance.

Alternatives/Enhancements: #

  • Materialized views store the result physically and can be refreshed periodically for better performance.
  • Temporary views or CTEs (Common Table Expressions) can be used for short-lived queries without creating permanent views.

In summary, a VIEW is a powerful tool for simplifying queries, securing data, and reusing logic, but careful design is needed for performance and update considerations.

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