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Describe the access control facilities of SQL.

      

Describe the access control facilities of SQL.

  

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KELVIN
Each database user is assigned an authorization identifier by the Database Administrator (DBA); usually, the identifier has an associated password, for obvious security reasons. Every SQL statement that is executed by the DBMS is performed on behalf of a specific user. The authorization identifier is used to determine which database objects that user may reference, and what operations may be performed on those objects. Each object that is created in SQL has an owner, who is identified by the authorization identifier. By default, the owner is the only person who may know of the existence of the object and perform any operations on the object.
Privileges are the actions that a user is permitted to carry out on a given base table or view. For example, SELECT is the privilege to retrieve data from a table and UPDATE is the privilege to modify records of a table. When a user creates a table using the SQL CREATE TABLE statement, he or she automatically becomes the owner of the table and receives full privileges for the table. Other users initially have no privileges on the newly created table. To give them access to the table, the owner must explicitly grant them the necessary privileges using the SQL GRANT statement. A WITH GRANT OPTION clause can be specified with the GRANT statement to allow the receiving user(s) to pass the privilege(s) on to other users. Privileges can be revoked using the SQL REVOKE statement.
When a user creates a view with the CREATE VIEW statement, he or she automatically becomes the owner of the view, but does not necessarily receive full privileges on the view. To create the view, a user must have SELECT privilege to all the tables that make up the view. However, the owner will only get other privileges if he or she holds those privileges for every table in the view.
kalvinspartan answered the question on July 4, 2018 at 17:08

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