Creating and using views
A view is a virtual table whose result set is derived from a query. In reality, a view is simply a SELECT statement that is saved with the name in the database. Views are used just like regular tables without incurring additional cost, unless you are indexing the view. We typically create views based on one or more tables, views, CTEs, table-valued functions, or a combination of them all. We can reference views in Transact-SQL statements in the same way tables are referenced. We can also perform DML operations on views. The typical uses of views include:
- A denormalized presentation of normalized data
- Limiting access to specific columns of the underlying tables
- Creating a reusable set of data
- Restricting users' access to sensitive data
Tip
You should avoid using
SELECT *in views, because when you do, the columns list is resolved each time you query the view. Moreover, the result set of the view query changes when the underlying table schema changes. A good practice...
