Examine the SQL statement that creates ORDERS table:
CREATE TABLE orders
(SER_NO NUMBER UNIQUE,
ORDER_ID NUMBER,
ORDER_DATE DATE NOT NULL,
STATUS VARCHAR2(10)
CHECK (status IN ('CREDIT', 'CASH')),
PROD_ID NUMBER
REFERENCES PRODUCTS(PRODUCT_ID),
ORD_TOTAL NUMBER,
PRIMARY KEY (order_id, order_date));
For which columns would an index be automatically created when you execute the above SQL statement? （）

A.No change is required to achieve the desired results.
B.SELECT ename, sal, 12*(sal+100) FROM emp;
C.SELECT ename, sal, (12*sal)+100 FROM emp;
D.SELECT ename, sal+100,*12 FROM emp;

A.The DESCRIBE DEPT statement displays the structure of the DEPT table.
B.The ROLLBACK statement frees the storage space occupied by the DEPT table.
C.The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist.
D.The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement.

A.COMMIT
B.MERGE
C.UPDATE
D.DELETE
E.CREATE
F.DROP...