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QUESTION NO: 9
You query DBA_CONSTRAINTS to obtain constraint information on the
HR_EMPLOYEES table:
SQL> select constraint_name, constraint_type, deferrable,
2> deferred, validated
3> from dba_constraints
4> where owner = 'HR' and table_name='EMPLOYEES';
CONSTRAINT_NAME C DEFERRABLE DEFERRED VALIDATED
--------------------- -------------- ----------- --------------
EMP_DEPT_FK R NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_EMAIL_NV C NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_EMAIL_UK U NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_EMP_ID_PK P NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_HIRE_DATE_NN C NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_JOB_FK R NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_JOB_NN C DEFERRABLE DEFERRED NOT VALIDATED
EMP_LAST_NAME_NN C NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_MANAGER_FK R NOT DEFERRABLE IMMEDIATE VALIDATED
EMP_SALARY_MIN C NOT DEFERRABLE IMMEDIATE VALIDATED
Which type of constraint is EMP_JOB_NN?
A. Check
B. Unique
C. Not null
D. Primary key
E. Foreign key
大家看看这个答案是什么,谢谢? |
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