Designing views

A view provides a different way of looking at the data in one or more tables; it is a named specification of a result table.

The specification is a SELECT statement that is run whenever the view is referenced in an SQL statement. A view has columns and rows just like a base table. All views can be used just like tables for data retrieval. Whether a view can be used in an insert, update, or delete operation depends on its definition.

The view type is established according to its update capabilities. The classification indicates the kind of SQL operation that is allowed against the view.

Referential and check constraints are treated independently. They do not affect the view classification.

For example, you might not be able to insert a row into a table due to a referential constraint. If you create a view using that table, you also cannot insert that row using the view. However, if the view satisfies all the rules for an insertable view, it will still be considered an insertable view. This is because the insert restriction is on the table, not on the view definition.

For more information, see the CREATE VIEW statement.