group by 子句不是分组依据

Question

我用 MSSQL 编写了以下查询：

Select customer.name, 
max(callnote.ID), 
CAST (callnote.NOTE as VARCHAR(100)) 
from callnote   
join CONTACT        
    on
        contact.ID=callnote.CONTACT_ID  
join CUSTOMER       
    on
        customer.ID=contact.CUSTOMER_ID 
where callnote.TYPE='n' and CUSTOMER.AcctClass>='1' 
group by customer.NAME, CAST (callnote.NOTE as VARCHAR(100)) 
order by customer.NAME

我希望每个客户名称只收到一条记录（最后一条记录）。（789 行，当我将 'CAST (callnote.NOTE as VARCHAR(100))' 排除在查询之外时得到的）我得到的是每个联系人的最后一个注释（11,500 多行）。我绞尽脑汁好几个小时，重写了这么多次。客户 table 和 callnote table 之间没有公共列。我如何让它只显示每个客户的最后一条注释？

Answer 1

我假设你想要来自 max callnote id 的笔记中的笔记？所以像这样：

Select
  C.name, 
  n.ID,
  n.NOTE
from
  CUSTOMER c
  outer apply (
    select top 1
      callnote.ID, 
      CAST (callnote.NOTE as VARCHAR(100)) 
    from
      CONTACT   
      join callnote 
        on contact.ID=callnote.CONTACT_ID and callnote.TYPE='n'  
    where
      c.ID=contact.CUSTOMER_ID
    order by 
      callnote.ID desc) n
where 
  c.AcctClass>='1' 
order by 
  c.NAME

所以这总是从该客户的最大 ID 中获取行。希望语法没问题，不能真正测试这个。

Answer 2

你能试试这个吗

SELECT Name, MAX(CallNoteID) CallNoteID, CallNote
FROM
(
SELECT Customer.Name, 
       CallNote.ID CallNoteID, 
       TRIM(CAST(CallNote.Note as VARCHAR(100))) CallNote
FROM CallNote   
JOIN Contact ON Contact.ID = CallNote.CONTACT_ID  
JOIN Customer ON Customer.ID = Contact.CUSTOMER_ID 
WHERE CallNote.Type = 'n' AND Customer.AcctClass >= '1' 
) A
GROUP BY Name, CallNote 
ORDER BY Name

group by 子句不是分组依据

group by clause not grouping by

mysql

sql-server

subquery

sql-server-2008