Which three statements are true about performing Data Manipulation Language (DML) operations on a view in an Oracle Database?

Views cannot be used to add or modify rows in an underlying table if the defining query of the view contains the DISTINCT keyword.
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 defining query of the view.
Views cannot be used to add rows to an underlying table if the table has columns with NOT NULL constraints lacking default values which are not referenced in the defining query of the view.
The WITH CHECK clause has no effect when deleting rows from the underlying table through the view.
Insert statements can always be done on a table through a view.
Views cannot be used to add or modify rows in an underlying table if the defining query of the view contains aggregating functions.

Answer(s): B,C,F

Examine the description of the EMPLOYEES table:

Which query is valid?

SELECT dept_id, MAX(AVG(salary)) FROM employees GROUP BY dept_id;
SELECT dept_id, AVG(MAX(salary)) FROM employees GROUP BY dept_id;
SELECT dept_id, join_date, SUM(salary) FROM employees GROUP BY dept_id, join_date;
SELECT dept_id, join_date, SUM(salary) FROM employees GROUP BY dept_id;

Answer(s): D

Which two statements are true about conditional INSERT ALL?

Each WHEN condition is tested for each row returned by the subquery.
The total number of rows inserted is always equal to the number of rows returned by the subquery.
A single WHEN condition can be used for multiple INTO clauses.
It cannot have an ELSE clause.
Each row returned by the subquery can be inserted into only a single target table.

Answer(s): C,D