SQL standard authorization

When the SQL standard authorization mode is enabled, object owners can use the GRANT and REVOKE SQL statements to set the user permissions for specific database objects or for specific SQL actions.

The SQL standard authorization mode is a SQL2003 compatible access control system. You enable the SQL standard authorization mode by setting the derby.database.sqlAuthorization property to TRUE.

While Derby has a simpler database access mode which can be set to provide users with full, read-only, or no access authorization, this simpler access mode is less appropriate for most client-server database configurations. When users or applications issue SQL statements directly against the database, the Derby SQL authorization mode provides a more precise mechanism to limit the actions that users can take on the database.

The GRANT statement is used to grant specific permissions to users. The REVOKE statement is used to revoke permissions. The grant and revoke privileges are:

DELETE
EXECUTE
INSERT
SELECT
REFERENCES
TRIGGER
UPDATE

When a table, view, function, or procedure is created, the person that creates the object is referred to as the owner of the object. Only the object owner and the database owner have full privileges on the object. No other users have privileges on the object until the object owner grants privileges to them.

Public and individual user privileges

The object owner can grant and revoke privileges for specific users or for all users. The keyword PUBLIC is used to specify all users. When PUBLIC is specified, the privileges affect all current and future users. The privileges granted and revoked to PUBLIC and to individual users are independent. For example, a SELECT privilege on table t is granted to both PUBLIC and to the user harry. The SELECT privilege is later revoked from user harry, but user harry has access to table t through the PUBLIC privilege.

Exception: When you create a view, trigger, or constraint, Derby first checks to determine if you have the required privileges at the user-level. If you have the user-level privileges, the object is created and is dependent on that user-level privilege. If you do not have the required privileges at the user-level, Derby checks to determine if you have the required privileges at the PUBLIC level. If you have the PUBLIC level privileges, the object is created and is dependent on that PUBLIC level privilege. After the object is created, if the privilege on which the object depends on is revoked, the object is automatically dropped. Derby does not try to determine if you have other privileges that can replace the privileges that are being revoked.

Example 1: User zhi creates table t1 and grants SELECT privileges to user harry on table t1. User zhi grants SELECT privileges to PUBLIC on table t1. User harry creates view v1 with the statement SELECT * from zhi.t1. The view depends on the user-level privilege that user harry has on t1. Subsequently, user zhi revokes SELECT privileges from user harry on table t1. As a result, the view harry.v1 is dropped.
Example 2: User anita creates table t1 and grants SELECT privileges to PUBLIC. User harry creates view v1 with the statement SELECT * from anita.t1. The view depends on the PUBLIC level privilege that user harry has on t1 since user harry does not have user-level privileges on table t1 when he creates the view harry.v1. Subsequently, user anita grants SELECT privileges to user harry on table anita.t1. The view harry.v1 continues to depend on PUBLIC level privilege that user harry has on t1. When user anita revokes SELECT privileges from PUBLIC on table t1, the view harry.v1 is dropped.

Permissions on views, triggers, and constraints

Views, triggers, and constraints operate with the permissions of the owner of the view, trigger, or constraint. For example, user anita wants to create a view using the following statement:

CREATE VIEW s.v(vc1,vc2,vc3)
	AS SELECT t1.c1,t1.c2,f(t1.c3)
  FROM t1 JOIN t2 ON t1.c1 = t2.c1 
	WHERE t2.c2 = 5

User anita needs the following permissions to create the view:

Ownership of the schema s, so that she can create something in the schema
Ownership of the table t1, so that she can allow others to see columns in the table
SELECT permission on column t2.c1 and column t2.c2
EXECUTE permission on function f

When the view is created, only user anita has SELECT permission on it. User anita can grant SELECT permission on any or all of the columns of view s.v to anyone, even to users that do not have SELECT permission on t1 or t2, or EXECUTE permission on f. User anita grants SELECT permission on view s.v to user harry. When user harry issues a SELECT statement on the view s.v, Derby checks to determine if user harry has SELECT permission on views.v. Derby does not check to determine if user harry has SELECT permission on t1, or t2, or EXECUTE permission on f.

Permissions on triggers and constraints work the same way as permissions on views. When a view, trigger, or constraint is created, Derby checks that the owner has the required permissions. Other users do not need to have those permissions to perform actions on a view, trigger, or constraint.

If the required permissions are revoked from the owner of a view, trigger, or constraint, the object is dropped as part of the REVOKE statement.

See the Derby Reference Manual for more information on the GRANT and REVOKE statements.