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
???
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