OCP-047external table

16. EMPDET is an external table containing the columns EMPNO and ENAME. Which
command would work in relation to the EMPDET table?
A.UPDATE empdet SET ename = 'Amit' WHERE empno = 1234.
B.DELETE FROM empdet WHERE ename LIKE 'J%'.
C.CREATE VIEW empvu AS SELECT * FROM empdept.
D.CREATE INDEX empdet_idx ON empdet(empno).
Answer: C

外部表的特点：

外部表不能做DML（UPDATE/INSERT/DELETE）操作，也不能在外部表上建立索引；但可以像访问内部数据表一样访问外部数据源数据。