SQL · Chapter 36 of 42

SQL Views

A VIEW is a saved SELECT query that behaves like a virtual table. Simplifies complex queries and hides implementation details.

A MATERIALIZED VIEW stores the result — much faster to read but needs periodic refresh.

Example 1 (sql)

CREATE VIEW top_customers AS
SELECT user_id, SUM(total) AS spent
FROM orders GROUP BY user_id
ORDER BY spent DESC;

SELECT * FROM top_customers LIMIT 10;

Output

Top 10 customers

Encapsulate a common aggregation.

Example 2 (sql)

CREATE MATERIALIZED VIEW daily_sales AS
SELECT DATE(created_at) AS day, SUM(total) AS revenue
FROM orders GROUP BY 1;

Output

Materialized view built

Fast dashboard queries — refresh with REFRESH MATERIALIZED VIEW.

Key points

Regular view = saved query.
Materialized view = stored result.
Great for security (expose only certain columns).
Refresh materialized views to keep data fresh.

💡 Note: MySQL didn't support materialized views natively for a long time — check your DB's docs.

SQL Views

Key points

📝 Quick Quiz