修改student表中学号为2015001的学生的姓名为“张三”

A.update student set sname=’ 张三’ where sid=’2015001’

B.update student set sname=张三 where sid=’2015001’

C.update student set sname=”张三” where sid=’2015001’

D.alter table student alter sname=’ 张三’ where sid=’2015001

正确答案：update student set sname=’ 张三’ where sid=’2015001’