Question

我有这个样本表：

ColA   ColB   ColC
CBCP    25    popx
ABC1    10    ppp1
ABC1    25    ppxx
CBCP    30    xm2x

从那里我想得到这些专栏

ColA   ColB   ColC
ABC1    25    ppxx
CBCP    30    xm2x

我想要的是获取max ColB的行..但是当我尝试在我的查询中包含ColC时出现错误：

select ColA, max(ColB), ColC
from tblCaseDev
where ColB > getdate() group by ColA

这是我的错误..

Msg 8120, Level 16, State 1, Line 1
Column 'tblCaseDev.ColC' is invalid in the
select list because it is not contained in either
an aggregate function or the GROUP BY clause.

希望有人能帮助我..提前感谢..

Answer 1

SELECT
CaseNo,Date,Remarks,

(SELECT max(cast(Date as datetime)) FROM tblCaseDev subc WHERE subc.CaseNo=c.CaseNo Group by c.CaseNo) AS MaxEntryDate

FROM tblCaseDev c 

order by CaseNo

Answer 2

您想使用row_number()窗口函数：

select CaseNo, "Date", Remarks
from (select t.*, row_number() over (partition by caseno order by date desc) as seqnum
      from tblCaseDev t
      where date > getdate()
     ) t
where seqnum = 1;

编辑：

如果您没有row_number()：

，您可以采用传统方式执行此操作

select t.*
from tblCaseDev t join
     (select caseno, max(date) as maxdate
      from tblCaseDev 
      group by caseno
     ) tsum
     on t.caseno = tsum.caseno and t.date = tsum.maxdate

Answer 3

您可以先创建聚合查询，然后将原始表连接到聚合查询。

示例：

SELECT
    A.CaseNo,
    A.Date,
    B.Remarks
FROM (
    SELECT
        CaseNo,
        MAX(Date)
    FROM tblCaseDev 
    WHERE Date > GetDate()
    GROUP BY CaseNo
) A 
JOIN tblCaseDev B
    ON A.CaseNo = B.CaseNo
    AND A.Date = B.Date

Answer 4

您可以使用ROW_NUMBER()为每个组ColA生成序号，并按ColB降序排序。

SELECT     ColA, ColB, ColC
FROM 
          (
               SELECT    ColA, ColB, ColC,
                         ROW_NUMBER() OVER(PARTITION BY ColA 
                                           ORDER BY ColB DESC) rn
               FROM tablename
          ) x
WHERE     rn = 1

SQLFiddle Demo

如果您希望获得与ColB相关的多条记录，您可能需要将其更改为DENSE_RANK()。

TSQL Ranking Functions

如何使用聚合列获取非聚合列的值？

4 个答案: