Beginning SQL

Betsey also grants privileges to Jim on tblPersonnel using this statement:
GRANT UPDATE, DELETE
ON tblPersonnel
TO usrJim
The first thing to notice is that usrJim now has all privileges on tblPersonnel and can select, update,
insert, or delete records in tblPersonnel. You subsequently revoke some of the privileges that you
granted to Jim with the following statement:
REVOKE UPDATE
ON tblPersonnel
FROM usrJim
Notice that even though you revoked the UPDATE privilege that you gave Jim, he still has full privileges
on tblPersonnel because Betsey also gave him UPDATE privileges. You subsequently revoke the rest of
the privileges you gave Jim:
REVOKE SELECT, INSERT
ON tblPersonnel
FROM usrJim
Jim still has all the privileges that Betsey granted him and can still perform updates and deletes on
tblPersonnel using those privileges.
Another scenario, however, must be considered, which is how the GRANT chain is handled by the DBMS.
Revoking GRANT
Suppose that Jim issues a GRANT to Sue WITH GRANT OPTION:
GRANT SELECT
ON tblPersonnel
TO usrSue
WITH GRANT OPTION
Sue now has the ability to grant the SELECT privileges to another user and does so, issuing a GRANT to
Frank:
GRANT SELECT
ON tblPersonnel
TO usrFrank
Jim now revokes the GRANT from Sue:
REVOKE SELECT
ON tblPersonnel
FROM usrSue
SQL Security
In this case, it can be clearly established that Frank received his privileges because Sue had GRANT OPTION
privileges, and therefore when Sue loses her privileges on tblPersonnel, Frank also loses his privileges.
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