子查询返回的值超过1。子查询遵循=，！=，＆lt;，＆lt; =，＆gt;，＆gt; =时不允许这样做

Question

为什么我会收到错误：

  

子查询返回的值超过1。当子查询遵循=，！=，＆lt;，＆lt; =，＆gt;，＆gt; =或子查询用作表达式时，不允许这样做。

create view viewAss
as select a.kd_ass,m.nama
from mahasiswa m ,asisten a, honor h
where m.NIM = a.nim and a.kd_ass = h.kd_ass
group by a.kd_ass,m.nama,h.honors
having h.honors > (select avg(h.honors) from honor)

  

命令已成功完成。

但是，当我跑...

select * from viewAss

错误：

  

Msg 512，Level 16，State 1，Line 2   子查询返回的值超过1。当子查询遵循=，！=，＆lt;，＆lt; =，＆gt;，＆gt; =或子查询用作表达式时，不允许这样做。

Answer 1

create view viewAss
as 
 select a.kd_ass
       ,m.nama
from mahasiswa m 
INNER JOIN  asisten a   ON m.NIM = a.nim
INNER JOIN  honor h     ON a.kd_ass = h.kd_ass
group by a.kd_ass,m.nama,h.honors
having h.honors > avg(h.honors)