The view EMP_VIEW is created based on the EMP table as follows:
CREATE OR REPLACE VIEW emp_view AS
SELECT deptno
, SUM(sal) TOT_SAL
, COUNT(*) TOT_EMP
FROM emp;
GROUP BY deptno;
What happens when the command is used?
UPDATE emp_view
SET tot_sal = 20000
WHERE deptno = 10;
A: The base table cannot be updated through this view.
B: The TOT_SAL column in the EMP table is updated to 20000 for department 10.
C: The TOT_EMP column in the EMP table is updated to 20000 for department 10.
D: The SAL column in the EMP table is updated to 20000 for employees in department 10.
ANSWER: A
EXPLANATION: Answer A is correct because the user may not INSERT, DELETE, or UPDATE data on the table underlying the sample view if the SELECT statement creating the view contains GROUP BY, or a single-row operation.
INCORRECT ANSWERS:
B: TOT_SAL column in the EMP table will not be updated.
C: TOT_EMP column in the EMP table will not be updated for any rows.
D: UPDATE command does not contain SAL column for update.
