出自:Oracle认证
Examine the structure if the EMPLOYEES table: Column name Data Type Remarks EMPLOYEE_ID NUMBER NOT NULL, Primary Key EMP_NAME VARCHAR2(30) JOB_ID VARCHAR2(20) NOT NULL SAL NUMBER MGR_ID NUMBER References EMPLOYEE_ID column DEPARTMENT_ID NUMBER Foreign key to DEPARTMENT_ID column of the DEPARTMENTS table You need to create a view called EMP_VU that allows the user to insert rows through the view. Which SQL statement, when used to create the EMP_VU view, allows the user to insert rows?（）
A:CREATE VIEW emp_Vu AS SELECT employee_id, emp_name, department_id FROM employees WHERE mgr_id IN (102, 120);
B:CREATE VIEW emp_Vu AS SELECT employee_id, emp_name, job_id department_id FROM employees WHERE mgr_id IN (102, 120);
C:CREATE VIEW emp_Vu AS SELECT department_id, SUM(sal) TOTALSAL FROM employees WHERE mgr_id IN (102, 120) GROUP BY department_ id;
D:CREATE VIEW emp_Vu AS SELECT employee_id, emp_name, job_id, DISTINCT department_id FROM employees;
What is the result?（）
What is the result？（）
In which situation would you use this method of disk group creation?（）
What would be the status of the foreign key EMP_MGR_FK？（）
If both classes are in the correct directories for their packages，and the Mammal class correctly defines thefindSalmon（） method， which change allows this code to compile？（）
What is the result?（）