sqlserver left join的on中如何添加多个查询条件??

[sweetBug]

create table teacher
(
    tid    varchar(12)           not null,
    tname  varchar(20)           not null,
    constraint PK_TEACHER primary key (tid)
)
go

create table student
(
    xh     varchar(20)           not null,
    tid    varchar(12)           null    ,
    sname  varchar(20)           not null,
    constraint PK_STUDENT primary key (xh)
)
go


create index Relation_11_FK on student (tid)
go

alter table student
    add constraint FK_STUDENT_RELATION__TEACHER foreign key  (tid)
       references teacher (tid)
go

如上,我有两个表,teacher和student.我想用left join查出一个老师下有多少个学生.
如:select teacher.* , student.* from teacher left join student on teacher.tid = student.tid;
但是我想再加上一个条件在后面,如是id为'0001'的老师所带的学生,应该怎么加?
我直接在后面加上..from teacher left join student on teacher.tid = student.tid and teacher.tid = '001'没有任何效果, 它还是会将所有老师的全查出来??

[yrwx001]

select teacher.* , student.* from teacher left join student on teacher.tid = student.tid
 where teacher.tid = '001'

[wxg22526451]

用where。。
select teacher.* , student.* from teacher left join student on teacher.tid = student.tid
where teacher.tid = '001'

[昵称被占用了]

select teacher.* , student.* from teacher left join student on teacher.tid = student.tid where  teacher.tid = '001'

[webdou]

select teacher.* , student.* from teacher left join student on teacher.tid = student.tid
where teacher.tid = '0001'

另外，还有你说是“0001”，怎么条件上写的是‘001’呢，

[hyqwan11112]

"我直接在后面加上..from teacher left join student on teacher.tid = student.tid and teacher.tid = '001'没有任何效果, 它还是会将所有老师的全查出来??"
在on 后边and 添加条件是做连接时用，
此处你想限制老师的tid应该加在where 后边
即：

select teacher.* , student.* from teacher left join student on teacher.tid = student.tid where  teacher.tid = '001'

[sweetBug]

谢谢各位啦,居然是这么简单的问题...汗~
再谢,接分!