帮忙看道题目

kshaoye

Which three statements are true about performing Data Manipulation Language（DML）operations on a view in a Oracle Database？
A.Views cannot be used to add or modify rows in an underlying table if the defining query of the view contains aggregating functions.

B.Views cannot be used to add rows to an underlying table if the table has columns with NOT NULL costraints lacking default values which are not referenced in the column.

C.Views cannot be used to query rows from an underlying table if the table has a PRIMARY KEY and the PRIMARY KEY columns are not referenced in the defing query.

D.Insert statements can always be done no a table through a view.

E.Views cannot be used to add or modify rows in an underlying table if the defing query of the view contains the DISTINCT keyword.

F.The WITH CHECK clauses has no effect when deleting rows from the underlying table through the view.