oracle ocp 19c考题，科目082考试题(20)-set unused column

20、choose two:Examine the structure of the DEPARTMENTS tableName Null? Type------------------------DEPARTMENT NOT NULL NUMBER(4)DEPARTMENT_NAME NOT NULL VARCHAR2(30)MANAGER_ID NUMBER(6)LOCATION_ID NUMBER(4)COUNTRY VARCHAR2(20)You execute the following command:SQL> ALTER TABLE departmentsSET UNUSED (country);Which two statements are true?A) A new column, COUNTRY, can be added to the DEPARTMENTS table after executing the command.B) Indexes created on the COUNTRY column exist until the DROP UNUSED COLUMNS command is executed.C) Unique key constraints defined on the COUNTRY column are removed.D) Synonyms existing on the DEPARTMENTS table would have to be re-created.E) Views created on the DEPARTMENTS table that include the COUNTRY column are automatically modified and remain valid.source : cuug