Create View - ( Oracle Views )

In Oracle, a view is a virtual table that is created using a select query. The view is stored in the database schema and can be queried like a regular table. Views can be used to simplify complex queries, provide an additional layer of security, and enhance performance.

Syntax

The syntax for creating a view in Oracle is as follows:

CREATE [OR REPLACE] VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;

Here, CREATE is the keyword used to create the view, OR REPLACE is an optional clause used to replace an existing view with the same name, view_name is the name of the view, column1, column2, ... are the columns that are selected, table_name is the name of the table on which the view is based, and condition is an optional clause used to filter the data.

Example

Here is an example of creating a view in Oracle:

CREATE VIEW employee_details AS
SELECT first_name, last_name, salary
FROM employees
WHERE department_id = 30;

Output

The above query creates a view called employee_details that selects the first_name, last_name, and salary columns from the employees table where the department_id is 30.

Explanation

In the above example, we have created a view called employee_details that selects columns from the employees table based on a condition. When the view is queried, only the selected columns will be returned for employees in department 30.

Use

Views can be used to simplify complex queries by abstracting the underlying table structure. They can also be used to provide an additional layer of security by restricting access to certain columns or rows of a table. Views can also be used to enhance performance by pre-computing complex queries and storing the results as a view.

Important Points

• Views are virtual tables created using a select query.
• Views can be used to simplify complex queries, provide an additional layer of security, and enhance performance.
• Views are stored in the database schema and can be queried like a regular table.
• Views can be created using the CREATE VIEW statement.

Summary

In summary, views in Oracle are virtual tables that are created using a select query. They can be used to simplify complex queries, provide an additional layer of security, and enhance performance. Views are stored in the database schema and can be queried like regular tables. The syntax for creating a view in Oracle involves using the CREATE VIEW statement.