A. update user set id = u001; B. update user(id,username) values('u001 ','jack'); C. update user set id='u001',username='jack'; D. update into user set id = ' u001', username='jack';
ALTER TABLE student set grade=80; B. ALTER student set grade=80; C. UPDATE student set grade=80 where grade<80; D. UPDATE student set grade=80;
A. DROP B. SELECT C. UPDATE DELLETE
A. 分号 B. 逗号 C. 空格 D. 回车
A. 0 B. 1 C. NULL D. 多条