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Views

A VIEW in SQL is a virtual table based on the result-set of a SELECT query. Views are used to simplify complex queries, improve security by restricting access to specific data, and make query results easier to work with.

Creating a View

Use the CREATE VIEW statement to create a view. The syntax is:

CREATE VIEW ViewName AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;

Example: Creating a View

CREATE VIEW ActiveFreedomFighters AS
SELECT Name, City, BirthDate
FROM FreedomFighters
WHERE BirthDate < '1900-01-01';

Explanation: This view, named ActiveFreedomFighters, selects the names, cities, and birthdates of freedom fighters born before 1900.

Querying a View

You can query a view just like a regular table:

SELECT * FROM ActiveFreedomFighters;

Updating a View

To modify a view, use the ALTER VIEW statement:

ALTER VIEW ActiveFreedomFighters AS
SELECT Name, City, Contribution
FROM FreedomFighters
WHERE Contribution IS NOT NULL;

Dropping a View

To delete a view, use the DROP VIEW statement:

DROP VIEW ActiveFreedomFighters;

Do's and Don'ts

Do's

  • Use views to simplify complex queries and make them more readable.
  • Use views to enhance security by limiting access to specific data.
  • Document your views for easy understanding and maintenance.

Don'ts

  • Don't use views for performance optimization if the underlying query is inefficient.
  • Don't assume views always improve performance; test and evaluate first.
  • Don't create views with unnecessary complexity; keep them focused on specific needs.
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