Question

我试图从按客户ID和状态分组的表格中获取每个状态的最高结果，按时间排序。

给出的数据：

CustNo Date       Status
 1      2016-03-24 C
 1      2016-02-08 C
 1      2016-01-17 A
 1      2015-12-04 C
 2      2016-04-28 B
 2      2016-03-25 C
 2      2016-02-13 C
 2      2016-01-04 C
 3      2016-02-02 A
 3      2016-01-09 A
 3      2015-12-12 A
 3      2015-11-30 A

我希望输出看起来像这样：

CustNo Date       Status
1      2016-03-24 C
1      2016-01-17 A
1      2015-12-04 C
2      2016-04-28 B
2      2016-03-25 C
3      2016-02-02 A

如您所见，我希望每个客户的每个状态更改（如果有）的最新日期。我为客户2和3解决了这个问题，其中状态没有变化或状态永远不会改变，但对于客户1，状态已从C更改为A并返回到C，这是一个棘手的部分（至少对我来说））。我似乎总是将C状态组合在一起。

Answer 1

你可以试试这个。

With CTE as 
{
    select CustNo,
            DATE,
            Status,
            ROW_NUMBER () over (partition by CustNo order by date) as ord
    from tab
)

SELECT  CustNo,
        DATE,
        Status
FROM CTE
EXCEPT
SELECT  C1.CustNo,
        C1.DATE,
        C1.Status
FROM CTE C1
    INNER JOIN CTE C2 ON C1.CustNo = C2.CustNo 
                        AND C1.Status = C2.Status
                        AND C1.ord + 1 = C2.ord

Answer 2

您可以使用窗口函数ROW_NUMBER来计算组：

WITH cte AS (
  SELECT *,
     ROW_NUMBER() OVER(PARTITION BY CustNo ORDER BY Date) -
     ROW_NUMBER() OVER(PARTITION BY CustNo, Status ORDER BY Date) AS grp
  FROM mytable
)
SELECT CustNo, Status, MAX(Date) AS Date
FROM cte
GROUP BY CustNo, Status, grp
ORDER BY CustNo, Date DESC;

的 LiveDemo

输出：

╔════════╦════════╦═════════════════════╗ ║ CustNo ║ Status ║ Date ║ ╠════════╬════════╬═════════════════════╣ ║ 1 ║ C ║ 24.03.2016 00:00:00 ║ ║ 1 ║ A ║ 17.01.2016 00:00:00 ║ ║ 1 ║ C ║ 04.12.2015 00:00:00 ║ ║ 2 ║ B ║ 28.04.2016 00:00:00 ║ ║ 2 ║ C ║ 25.03.2016 00:00:00 ║ ║ 3 ║ A ║ 02.02.2016 00:00:00 ║ ╚════════╩════════╩═════════════════════╝

按时间顺序排列

2 个答案: