A view in SQL is a logical subset of data from one or more tables. View is used to restrict data access.
A view can contain all rows of a table or select rows from a table. A view can be created from one or many tables which depends on the written SQL query to create a view.
Views, which are kind of virtual tables, allow users to do the following:
Database views are created using the CREATE VIEW statement. Views can be created from a single table, multiple tables, or another view.
To create a view, a user must have the appropriate system privilege according to the specific implementation.
CREATE VIEW view_name AS SELECT column1, column2..... FROM table_name WHERE [condition];
CREATE VIEW cust_view AS SELECT name, age FROM customer;
SELECT * FROM cust_view;
View can be updated under certain conditions:
UPDATE CUSTOMERS_VIEW SET AGE = 24 WHERE name='Sachin';
Rows of data can be inserted into a view. The same rules that apply to the UPDATE command also apply to the INSERT command.
Here we can not insert rows in CUSTOMERS_VIEW because we have not included all the NOT NULL columns in this view, otherwise you can insert rows in a view in similar way as you insert them in a table.
Rows of data can be deleted from a view. The same rules that apply to the UPDATE and INSERT commands apply to the DELETE command.
DELETE FROM cust_view WHERE age = 24;
Obviously, where you have a view, you need a way to drop the view if it is no longer needed.
DROP VIEW view_name;