多项选择题
A. You cannot use IN operator in a condition that involves an outerjoin.
B. You use (+) on both sides of the WHERE condition to perform an outerjoin.
C. You use (*) on both sides of the WHERE condition to perform an outerjoin.
D. You use an outerjoin to see only the rows that do not meet the join condition.
E. In the WHERE condition, you use (+) following the name of the column in the table without matching rows, to perform an outerjoin.
F. You cannot link a condition that is involved in an outerjoin to another condition by using the OR operator.
单项选择题 Which statement creates a new user? （）
单项选择题 You need to change the definition of an existing table. The COMMERCIALS table needs its DESCRIPTION column changed to hold varying length characters up to 2000 bytes. The column can currently hold 1000 bytes per value. The table contains 20000 rows. Which statement is valid?（）
单项选择题 What does the TRUNCATE statement do?（）