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Core Code Modern Dev Handbook

SQL Views

A VIEW is a virtual table based on a SELECT query. It simplifies complex queries and can help with security and reuse.
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SQL Views

A view is a virtual table based on the result set of a SQL query. A view does not store data itself (in most databases); it stores the query definition and returns data when queried.

Why Use Views?

  • Simplify complex queries (especially with JOINs)
  • Reuse common query logic
  • Provide a security layer by exposing only selected columns/rows
  • Make reporting queries easier to maintain

Create a View

CREATE VIEW view_name AS
SELECT column1, column2
FROM table_name
WHERE condition;

Example: Active Customers View

CREATE VIEW active_customers AS
SELECT id, name, email, country
FROM customers
WHERE status = 'active';

Query a View

You query a view like a normal table:

SELECT *
FROM active_customers
ORDER BY name;

Example: View with JOIN

Views are great for hiding JOIN complexity.

CREATE VIEW customer_orders AS
SELECT c.id AS customer_id,
       c.name AS customer_name,
       o.id AS order_id,
       o.order_date
FROM customers AS c
JOIN orders AS o
  ON c.id = o.customer_id;

Updateable Views (Important Note)

Some views can be updated (INSERT/UPDATE/DELETE) if they meet certain rules. Views that include complex joins, aggregates, or GROUP BY are often not updateable.

Replace or Change a View

Many systems support CREATE OR REPLACE VIEW. If not available, you can drop and recreate the view.

CREATE OR REPLACE VIEW active_customers AS
SELECT id, name, email, country
FROM customers
WHERE status = 'active';

Drop a View

DROP VIEW active_customers;

Common Mistakes

  • Assuming a view stores data (it usually does not)
  • Forgetting that views depend on underlying tables and columns
  • Using views as a replacement for proper indexing

Best Practice

Use views to standardize common queries and to expose only the data that should be queried. Keep view definitions simple and well-named.

Next Step

Continue with SQL Injection to learn how to protect your application from dangerous SQL attacks.

SQL Injection →