Views

Views are pseudo-tables, not physically materialized.
A view can represent a subset of a real table, selecting certain columns or certain rows from an ordinary table. It can also represent joined tables.

Because views are assigned separate permissions, you can use them to restrict table access so that users see only specific rows or columns of a table.

Although views are not real tables, they appear as ordinary tables to SELECT.
Views should be read only: the system should not allow an insert, update, or delete on a view.

CREATE VIEW will define a view of a table:

CREATE VIEW view [ ( column_name_list ) ] AS SELECT query column_name_list is an optional list of names to be used for columns of the view. If given, these names override the column names that would be deduced from the SQL query.

Example:

CREATE VIEW bio_stud AS SELECT name, diploma FROM stud WHERE diploma = 'bio' ; SELECT * FROM bio_stud ; name | diploma ------+--------- fred | bio tom | bio lisa | bio

A view can be removed with DROP VIEW, example:

DROP VIEW bio_stud;