Oracle 计算平均速率之间的差异

我需要找出过去12个月

员工

表和非

员工

表的平均比率之间的差异

以下是我到目前为止的情况：

select  person.pid, 
        person.firstname, 
        person.lastname,
        AVG(RATING_RECORD.RATE)
from person, 
     client, 
     staff, 
     policy,
     COVERAGE,
     RATING_RECORD
where person.PID = client.PID  and  
      staff.pid = person.pid and 
      policy.SID =staff.SID and 
      COVERAGE.PNO = policy.PNO and
      COVERAGE.COID = RATING_RECORD.COID;

现在我来谈谈这个问题

select  person.pid,
    person.FIRSTNAME,
    AVG(RATING_RECORD.RATE)
from person 
    join client on person.pid = client.pid 
    join staff on person.pid = staff.pid  
    join policy on staff.sid = policy.sid
    join coverage on policy.PNO = coverage.PNO
    join RATING_RECORD on coverage.COID = RATING_RECORD.COID
where policy.EXPIRYDATE between '12-NOV-13' and '12-nov-14 '
group by person.PID, person.FIRSTNAME;

但问题是它只显示了3个结果，而不是整个列表

离开我的评论，我带着客户加入进来，提出了 13结果

select  person.pid,
person.FIRSTNAME,
AVG(RATING_RECORD.RATE)
from person 

join staff on person.pid = staff.pid  
join policy on staff.sid = policy.sid
join coverage on policy.PNO = coverage.PNO
join RATING_RECORD on coverage.COID = RATING_RECORD.COID

where policy.EXPIRYDATE between '12-NOV-13' and '12-nov-14 '
group by person.PID, person.FIRSTNAME;

---

但是我如何让客户返回给我员工和非员工？

请您更明确地定义员工和非员工。谢谢，我不知道你所说的定义是什么意思？你想显示哪些列？数据库如何表示一个人是员工还是非员工？例如，一个人可以既是员工又是客户吗？目前，您的查询将只返回那些

PID

s在

STAFF

和

CLIENT

表中都找到的人。哦，对了，我现在更明白了，我想同时显示员工和非员工，如果他们都在，请显示两次