create table class(
classid int primary key ,
class int);insert into class values(1,111);
insert into class values(2,222);
insert into class values(3,333);create table student(
studentid int primary key,
classid int,
name varchar(20)
);insert into student values(1,1,'zzz');
insert into student values(2,1,'aaa');
insert into student values(3,2,'ccc');
insert into student values(4,2,'bbb');
insert into student values(5,1,'ggg');
insert into student values(6,3,'fff');
insert into student values(7,3,'hhh');create table Temp(
classid int,
name varchar(20));insert into Temp values(1,'zzz');
insert into Temp values(1,'aaa');
insert into Temp values(2,'ccc');
insert into Temp values(3,'hhh');
把不在Temp表中的Name设为null
classid int primary key ,
class int);insert into class values(1,111);
insert into class values(2,222);
insert into class values(3,333);create table student(
studentid int primary key,
classid int,
name varchar(20)
);insert into student values(1,1,'zzz');
insert into student values(2,1,'aaa');
insert into student values(3,2,'ccc');
insert into student values(4,2,'bbb');
insert into student values(5,1,'ggg');
insert into student values(6,3,'fff');
insert into student values(7,3,'hhh');create table Temp(
classid int,
name varchar(20));insert into Temp values(1,'zzz');
insert into Temp values(1,'aaa');
insert into Temp values(2,'ccc');
insert into Temp values(3,'hhh');
把不在Temp表中的Name设为null
更新姓名不在temp表中的student name