oracle view deletion

A view in Oracle database is a virtual table. It does not contain any data, but is the result of taking data from one or more tables and performing operations such as arranging, grouping, calculation, etc., as a virtual table for users Query and operate. Views are widely used in Oracle database, but sometimes we need to delete a view. This article will introduce how to delete a view in Oracle database.

Things to note before deleting a view

Before deleting a view, you need to consider the following points:

1. Deleting a view will not affect the data in the underlying table. A view is just a virtual table representation based on the underlying table data. Deleting the view will not cause the data in the underlying table to be lost.
2. Deleting a view requires authorization. Only users or administrators with DROP ANY VIEW permission can delete any view.
3. Deleting views requires caution. Once a view is dropped, it is impossible to restore it again from the underlying table. Therefore, you must consider carefully before performing the DROP VIEW operation.

How to delete a view

Oracle's DROP VIEW statement is used to delete an existing view. The syntax is as follows:

DROP VIEW view_name;

where view_name is the name of the view you want to delete.

For example, if we want to delete the view named EMP_SALARY, we can execute the following command:

DROP VIEW EMP_SALARY;

When the view is deleted, any query on it will return an error.

In addition, if the view is used by multiple users or programs at the same time, deleting the view may cause errors for these users or programs. Therefore, before deleting a view, make sure it is no longer in use.

Operations after deleting a view

Once a view is deleted, the following actions will occur:

1. No user or program can anymore use the view.
2. The definition of this view will be deleted from the data dictionary.
3. Any authorizations associated with this view will be removed from the database. For example, if you granted other users access to the view, those grants will also be removed.

Summary

View is a very important feature in Oracle database, which can help us simplify complex queries and analysis, improve query efficiency and data security. However, when using a view, we also need to pay attention to its deletion operation, ensure that the operation is correct and careful, and confirm that the view is no longer used before operating.

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