SQL多表连接查询错误

use master
go

if exists (select * from sysdatabases where name ='testDB')
drop database testDB
go
create database testDB

go

-----------------stu
if exists (select * from sysobjects where name='un_sno')
alter table t_stu drop constraint un_sno
if exists (select * from sysobjects where name='fk_sno')
alter table t_score drop constraint fk_sno
if exists (select * from sysobjects where name='t_stu')
drop table t_stu
go

create table t_stu(
 sno varchar(8) primary key,
 sname varchar(12) not null,
 sclass varchar(20),
 sgrade int
)
go

------------------subject
if exists (select * from sysobjects where name='fk_subid')
alter table t_score drop constraint fk_subid
if exists (select * from sysobjects where name='t_subject')
drop table t_subject
go

create table t_subject(
 subid int primary key identity(1,1),
 suname varchar(16)
)
go

-----------------score
if exists (select * from sysobjects where name='t_score')
drop table t_score
go

create table t_score(
 scid int primary key identity(1,1),
 sno varchar(8) not null,
 subid int,
 sscore int
)
go

---------------constraints

alter table t_stu add constraint un_sno unique (sno)
go

alter table t_score add constraint fk_sno foreign key (sno)
 references t_stu(sno)
go

alter table t_score add constraint fk_subid foreign key (subid)
 references t_subject(subid)
go

---------------insert value
insert into t_stu values('001','tom','s3',2)
insert into t_stu values('002','jack','s4',3)
insert into t_stu values('003','ann','e3',3)
insert into t_stu values('004','jim','e4',6)

insert into t_subject values('历史')
insert into t_subject values('哲学')
insert into t_subject values('英语')

insert into t_score values('001',2,89)
insert into t_score values('001',3,49)

insert into t_score values('003',3,83)
insert into t_score values('001',1,84)
---------------display
select * from t_stu
select sno ,sname from t_stu
select * from t_score
select * from t_subject
--------------result
select a.sno as '学号' ,a.sname,b.suname as '学科',c.sscore as '分数' from t_score as c
 left join t_score as a on a.sno=c.sno
 left join t_subject as b on b.subid=c.subid

//朋友您好，本人已经复制你代码在本机上建数据库，测试通过了。望采纳。select 语句该下就得了。不懂再问，谢谢

select a.sno as '学号' ,a.sname as '姓名',b.suname as '学科',c.sscore as '分数'

from t_stu as a join t_score as c on a.sno=c.sno join t_subject as b on b.subid=c.subid

select a.sno as '学号' ,a.sname,b.suname as '学科',c.sscore as '分数' from t_score as c
 left join t_score as a on a.sno=c.sno
 left join t_subject as b on b.subid=c.subid

t_score 表里没有sname这个字段。你搞错了把

sqlserver~应该会显示那一行报错才对啊~~

你别一起执行，慢慢一块一块的执行，把具体出错的代码贴出来~

这样贴一堆，很不好看的