Examine the structure of the EMPLOYEES table:
EMPLOYEE_ID NUMBER NOT NULL, Primary Key
EMP_NAME VARCHAR2(30)
JOB_ID NUMBER\\
SAL NUMBER
MGR_ID NUMBER References EMPLOYEE_ID column
DEPARTMENT_ID NUMBER Foreign key to DEPARTMENT_ID column of the
DEPARTMENTS table
You created a sequence called EMP_ID_SEQ in order to populate sequential values for the
EMPLOYEE_ID column of the EMPLOYEES table.
Which two statements regarding the EMP_ID_SEQ sequence are true? (Choose two.)
A.
You cannot use the EMP_ID_SEQ sequence to populate the JOB_ID column.
B.
The EMP_ID_SEQ sequence is invalidated when you modify the EMPLOYEE_ID column.
C.
The EMP_ID_SEQ sequence is not affected by modifications to the EMPLOYEES table.
D.
Any other column of NUMBER data type in your schema can use the EMP_ID_SEQ sequence.
E.
The EMP_ID_SEQ sequence is dropped automatically when you drop the EMPLOYEES table.
F.
The EMP_ID_SEQ sequence is dropped automatically when you drop the EMPLOYEE_ID column.
Explanation:
the EMP_ID_SEQ sequence is not affected by modification to the EMPLOYEES
table. Any other column of NUMBER data type in your schema can use the EMP_ID_SEQ
sequence.Incorrect answer:
A EMP_ID_SEQ sequence can be use to populate JOB_ID
B EMP_ID_SEQ sequence will not be invalidate when column in EMPLOYEE_ID is modify.
E EMP_ID_SEQ sequence will be dropped automatically when you drop the EMPLOYEES
table.
F EMP_ID_SEQ sequence will be dropped automatically when you drop the EMPLOYEE_ID
column.
Refer: Introduction to Oracle9i: SQL, Oracle University Study Guide, 12-4