单项选择题
A. It returns versions of rows only within a transaction.
B. It can be used in subqueries contained only in a SELECT statement.
C. It will return an error if the undo retention time is less than the lower bound time or SCN specified.
D. It retrieves all versions including the deleted as well as subsequently reinserted versions of the rows.
单项选择题 View the Exhibit and examine the structure of the EMP table. You executed the following command to add a primary key to the EMP table： ALTER TABLE emp ADD CONSTRAINT emp_id_pk PRIMARY KEY （emp_id） USING INDEX emp_id_idx； Which statement is true regarding the effect of the command？（）
单项选择题 The user SCOTT who is the owner of ORDERS and ORDERJTEMS tables issues the following GRANT command： GRANT ALL ON orders， order_items TO PUBLIC； What correction needs to be done to the above statement？ （）
单项选择题 View the Exhibit and examine the data in ORDERS_MASTER and MONTHLYjDRDERS tables. What would be the outcome of the above statement？（）