-- 建测试表
create table houyichong
(id1 int not null,
 id2 int not null,
 de varchar(10)
 constraint pk_houyichong primary key(id1,id2)
 )

-- 动态产生脚本
declare @tab varchar(200),@sql varchar(5000)

select @tab='houyichong'

select @sql='alter table ['+@tab+'] add constraint ['
+name+'] '
from sys.objects
where parent_object_id=object_id('houyichong')

select @sql=@sql+' primary key('+
(select cast(
(select name+','
from (select c.name
from sys.indexes a
inner join sys.index_columns b
on a.[object_id]=b.[object_id]
inner join sys.columns c
on b.[object_id]=c.[object_id]
and b.index_column_id=c.column_id
where a.[object_id]=object_id(@tab)
and a.is_primary_key=1) t
for xml path('')) as varchar(20)))

select @sql=left(@sql,len(@sql)-1)+') '

-- 打印
print @sql

--> 结果
alter table [houyichong] add constraint [pk_houyichong]  primary key(id1,id2) 

-- 执行
exec(@sql)