SQLite - Views


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A view is nothing more than a SQLite statement that is stored in the database with an associated name. It is actually a composition of a table in the form of a predefined SQLite query.

A view can contain all rows of a table or selected rows from one or more tables. A view can be created from one or many tables which depends on the written SQLite query to create a view.

Views which are kind of virtual tables, allow the users to −

  • Structure data in a way that users or classes of users find natural or intuitive.

  • Restrict access to the data such that a user can only see limited data instead of a complete table.

  • Summarize data from various tables, which can be used to generate reports.

SQLite views are read-only and thus you may not be able to execute a DELETE, INSERT or UPDATE statement on a view. However, you can create a trigger on a view that fires on an attempt to DELETE, INSERT, or UPDATE a view and do what you need in the body of the trigger.

Creating Views

SQLite views are created using the CREATE VIEW statement. SQLite views can be created from a single table, multiple tables, or another view.

Following is the basic CREATE VIEW syntax.

CREATE [TEMP | TEMPORARY] VIEW view_name AS
SELECT column1, column2.....
FROM table_name
WHERE [condition];

You can include multiple tables in your SELECT statement in a similar way as you use them in a normal SQL SELECT query. If the optional TEMP or TEMPORARY keyword is present, the view will be created in the temp database.

Example

Consider COMPANY table with the following records −

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0

Following is an example to create a view from COMPANY table. This view will be used to have only a few columns from COMPANY table.

sqlite> CREATE VIEW COMPANY_VIEW AS
SELECT ID, NAME, AGE
FROM  COMPANY;

You can now query COMPANY_VIEW in a similar way as you query an actual table. Following is an example −

sqlite> SELECT * FROM COMPANY_VIEW;

This will produce the following result.

ID          NAME        AGE
----------  ----------  ----------
1           Paul        32
2           Allen       25
3           Teddy       23
4           Mark        25
5           David       27
6           Kim         22
7           James       24

Dropping Views

To drop a view, simply use the DROP VIEW statement with the view_name. The basic DROP VIEW syntax is as follows −

sqlite> DROP VIEW view_name;

The following command will delete COMPANY_VIEW view, which we created in the last section.

sqlite> DROP VIEW COMPANY_VIEW;


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