Data Control Language (DCL)
The Data Control Language (DCL) statements are used to control access to data and database objects. DCL includes the following statements:
- GRANT – gives permissions to users.
- REVOKE – removes granted or denied permissions.
- DENY – explicitly denies permissions.
GRANT
Use GRANT to give a principal access rights to a securable.
GRANT SELECT, INSERT ON dbo.TableA TO [UserA];| Clause | Description |
|---|---|
SELECT, INSERT | Permissions being granted. |
ON dbo.TableA | The object to which permissions apply. |
TO [UserA] | The principal receiving the permissions. |
REVOKE
Removes previously granted or denied permissions.
REVOKE INSERT ON dbo.TableA FROM [UserA];If a permission is not explicitly granted, revoking has no effect.
DENY
Explicitly denies a permission. Denied permissions take precedence over granted ones.
DENY SELECT ON dbo.TableA TO [UserB];Use with caution, as it overrides any future GRANT statements for the same permission.
Best Practices
- Prefer role‑based security: grant permissions to roles, then add users to roles.
- Use
DENYsparingly; it can create complex permission hierarchies. - Document all DCL changes in a change‑log for audit compliance.