What is define view?

A view in database management systems is a virtual table that provides a specific perspective on data from one or more tables. A view is defined based on a query that retrieves and displays data from one or more tables in the database. This query can be defined using SQL or other query languages supported by the database management system.

Views are used to simplify queries and to provide a level of security by filtering out sensitive data that certain users do not have permission to access. Views can also be used to simplify complex queries by aggregating or summarizing data from multiple tables into a single view.

Once a view is defined, it can be used in the same way as a regular table, including querying and joining with other tables. However, changes made to the data in the view are not directly made to the underlying tables, except in some cases where the view is updatable.