单项选择题
A. CREATIVE USER susan;
B. CREATIVE OR REPLACE USER susan;
C. CREATE NEW USER susan DEFAULT
D. CREATE USER susan IDENTIFIED BY blue;
E. CREATE NEW USER susan IDENTIFIED BY blue;
F. CREATE OR REPLACE USER susan IDENTIFIED BY blue;
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?（）
单项选择题 Which is an /SQL*Plus command? （）