Examine the structure of the EMP_DEPT_VU view:
Column Name Type Remarks
EMPLOYEE_ID NUMBER From the EMPLOYEES table
EMP_NAME VARCHAR2(30) From the EMPLOYEES table
JOB_ID VARCHAR2(20) From the EMPLOYEES table
SALARY NUMBER From the EMPLOYEES table
DEPARTMENT_ID NUMBER From the DEPARTMENTS table
DEPT_NAME VARCHAR2(30) From the DEPARTMENTS table
Which SQL statement produces an error?（）

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? （）