() . , , SQL . , , , - ( SQL). , , , , , . , , CHECK OPTION CHECK ( 22 ). , , . , Adrian Customers, Diane.Customers:
CREATE SYNONYM Customers FOR Diane.Customers;
SQL, : Diane.Customers Adrian.Customers. , Customers, SQL .
, , , . , , . , . , Customers,
CREATE PUBLIC SYNONYM Customers FOR Customers;
, , . , , DBA. , , , . , . PUBLIC, .
DROP SYNONYM. , , , DBA. , , Clients, Customers, Adrian
DROP SYNONYM Clients;
, , .
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SQL , , .
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, ( DBS Data Base Spaces), SQL .
DBS CREATE DBSPACE ( DBS), ACQUIRE DBSPACE ( DBS) CREATE TABLESPACE ( ), . DBS , DBS. , , DBS. DBS Sampletables, :
CREATE DBSPACE Sampletables
(pctindex 10,
pctfree 25);
pctindex , DBS , . Pctfree DBS, , (ALTER TABLE , ; , ). , , . , DBS, . DBS , .
DBS , . , , Diane Sampletables :
GRANT RESOURCE ON Sampletables TO Diane;
. DBS, , .
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DBS, , . , , , , , , DBS.
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SQL, DML DROP TABLE, . , , , . , , .
, SQL. , , COMMIT WORK ROLLBACK WORK. COMMIT , ROLLBACK . COMMIT ROLLBACK. . , , COMMIT ROLLBACK
COMMIT WORK;
-
ROLLBACK WORK;
, , AUTOCOMMIT. , . , , "" . , , :
SET AUTOCOMMIT ON;
:
SET AUTOCOMMIT OFF;
AUTOCOMMIT, .
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, , , , . , , , . , , Motika . , , - . ( , , ANSI, , , . .)
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, snum NULL, , Peel. :
UPDATE Orders
SET snum = NULL
WHERE snum = 1004;
UPDATE Cudomers
SET snum = 1001
WHERE snum = 1004;
DELETE FROM Salespeople
WHERE snum = 1004;
Motika (, , , ), , , , .
, , . COMMIT, COMMIT ROLLBACK.