我认为你在这一行中犯了一个简单的错误：

 streamname  varchar （  10 ）约束 stream_stname_fk 外来  key  参考 stream（ stramname ）

它应该是：

 streamname  varchar （ 10 ）约束 stream_stname_fk  foreign   key   references  stream（ streamname ）

create database muni
use muni
create table stream
(
streamname varchar(10) constraint stream_strname_pk primary key
)
select *from stream
create table branch
(
branchid int identity constraint branch_bid_pk primary key,
branchname varchar(20) not null,
streamname varchar(10) constraint stream_strname_fk foreign key references stream(streamname)
)
select *from branch
create table semistar
(
semistarid int identity constraint semistar_sid_pk primary key,
semistarname varchar(30) not null,
streamname varchar(10)constraint  stream_stname_fk foreign key references stream(stramname)
)
select *from semistar

Hi,

I think that you have a made a simple mistake in this line:

streamname varchar(10)constraint stream_stname_fk foreign key references stream(stramname)

It should be:

streamname varchar(10)constraint stream_stname_fk foreign key references stream(streamname)