17、Database Views and Materialized Views: Concepts, Optimization, and Implementation

Database Views and Materialized Views: Concepts, Optimization, and Implementation

1. Database View Basics

1.1 References in Views

The purpose of a reference is to ensure that data referenced from one table exists in another. When working with views, which are based on other tables, the values you reference in a view should also exist in the original table. If you’re solely using a view and need a new reference, don’t add it directly to the view. Instead, find the appropriate base table and reference that table.

1.2 Constraints in Views

Constraints are unnecessary in views. The purpose of a table constraint is to indicate that a row with certain properties is invalid and should not exist in the table. In a view, you can filter ou