DCL Full Form - Data Control Language

The full form of DCL is Data Control Language in Structured Query Language (SQL). DCL commands are used to control privileges in the database. The privileges (right to access the data) are required for performing all the database operations, like creating tables, views, or sequences. DCL statements are used to perform the work related to the rights, permissions, and other control of the database system.

There are two types of privileges in the database:

• System Privilege
• Object Privilege

Need Of DCL commands

• Unauthorized access to the data should be prevented in order to achieve security in our database
• DCL commands maintain the database effectively than anyone else other than database administrator is not allowed to access the data without permission.
• These commands provide flexibility to the data administrator to set and remove database permissions in granular fashion.

Commands in DCL

The two most important DCL commands are GRANT and REVOKE.

GRANT

This command is used to grant permission to the user to perform a particular operation on a particular object. If we are a database administrator and we want to restrict user accessibility such as one who only views the data or may only update the data.

we can give the privilege permission to the users according to our wish.

Syntax

GRANT privilege_list
ON Object_name
TO user_name;

REVOKE

This command is used to take permission/access back from the user. If we want to return permission from the database that we have granted to the users at that time we need to run REVOKE command.

Syntax

REVOKE privilege_list
ON object_name
FROM user_name;

Following commands are granted to the user as a Privilege List:

• EXECUTE
• UPDATE
• SELECT
• DELETE
• ALTER
• ALL

Advantages Of DCL commands

• It allows to restrict the user from accessing data in database.
• It ensures security in database when the data is exposed to multiple users.
• It is the wholesome responsibility of the data owner or data administrator to maintain the authority of grant and revoke privileges to the users preventing any threat to data.
• It prevents other users to make changes in database who have no access to Database

Disadvantages Of DCL commands

• Limited Functionality: DCL targets only restriction of access while other functions like manipulation of data will not be available.
• Security Risks: One can land up in assigning privileges to wrong users by improper use of `GRANT` and may not revoke the unnecessary privileges through `REVOKE hence making the data vulnerable to unauthorized users.
• Complex Permission Management: This brings a challenge when it comes to handling permission since the databases are large in the current world.
• No Data Handling: DCL cannot perform an ‘Insert statement’, ‘Update statement’ or ‘Delete statement’.
• Dependent on Other SQL Commands: It can also be noted that DCL is only useful when DML and DDL operations have been performed.

Conclusion

DCL is one of the sublanguages within SQL, alongside DDL (Data Definition Language), DML (Data Manipulation Language), and DQL (Data Query Language). Its primary purpose is to manage administrative tasks associated with controlling user access and permissions within the database.