What Is a View in SQL?

A SQL view is a saved SELECT statement stored in the database catalog that returns a virtual table each time it’s queried, without storing duplicate data.

How Does a SQL View Work?

The database engine rewrites queries against a view into the underlying SELECT logic at runtime, retrieving the latest base-table rows. No data duplication occurs.

Why Use SQL Views?

Views centralize complex joins or filters, enforce row-level security, and give analysts a stable interface even when the physical schema changes.

How Do You Create a View in SQL?

Use CREATE VIEW followed by the view name and a valid SELECT. Optionally add column aliases, WITH clauses, or SECURITY DEFINER for permission control.CREATE VIEW sales_q1 AS
SELECT order_id, customer_id, amount
FROM orders
WHERE order_date BETWEEN '2024-01-01' AND '2024-03-31';

Can You Update Data Through a View?

Yes, if the view maps 1-to-1 to a single base table without aggregates or DISTINCT. Otherwise, the database blocks DML or requires an INSTEAD OF trigger.

What Are the Performance Implications of Views?

Views add minimal overhead; the optimizer inlines them. Materialized views, however, store results physically and need refresh strategies.

When Should You Use Materialized vs. Normal Views?

Choose materialized views for heavy aggregations queried often with low update frequency; use standard views for realtime data and lightweight logic.

How Do Views Improve Security?

Grant users SELECT on a view instead of the base table to expose only permitted columns or rows, implementing least-privilege access.

What Are Common Pitfalls When Using Views?

Nesting too many views, hiding inefficient joins, or forgetting to update dependencies after schema changes can slow queries or break reports.

How Does Galaxy Help You Work With Views?

Galaxy’s AI copilot autocompletes CREATE VIEW statements, suggests column aliases, and surfaces lineage so teams can endorse and reuse trusted views.