根据中断条件将多行折叠成一行

Question

我有一个听起来很简单的要求，现在已经难住了我一天左右，所以是时候寻求专家的帮助了。

我的要求是根据中断条件将多行简单地汇总成一行 - 当这些列中的任何一个更改员工 ID、津贴计划、津贴金额或截止日期时，该行将被保留，如果有道理的话。

示例源数据集如下所示：

折叠行后的目标数据应如下所示：

如您所见，我不需要任何类型的运行总计计算，我只需要将行折叠成每个来自 date/to 日期组合的记录。

到目前为止，我已经使用 GROUP BY 和 MIN 函数尝试了以下 SQL

select [Employee ID], [Allowance Plan], 
       min([From Date]), max([To Date]), [Allowance Amount] 
from   [dbo].[#AllowInfo] 
group by [Employee ID], [Allowance Plan], [Allowance Amount]

但这只给了我一行，没有考虑中断条件。

我需要做什么才能正确地汇总记录（如果这不是正确的术语，请纠正我）考虑到中断条件？

感谢任何帮助。

谢谢。

Answer 1

请注意，您的测试数据并没有很好地运用算法 - 例如您只有一名员工，一个计划。另外，正如您所描述的，您最终会得到 4 行，因为日期在 7->8、8->9、9->10 和 10->11 之间发生了变化。

但我可以看到您正在尝试做什么，所以这至少应该让您走上正轨，并且 returns 预期的 3 行。我将组的末尾设为 employee/plan/amount 已更改的位置，或者 todate 不为空的位置（或者我们到达数据末尾的位置）

CREATE TABLE #data
(
    RowID INT,
    EmployeeID INT,
    AllowancePlan VARCHAR(30),
    FromDate DATE, 
    ToDate DATE,
    AllowanceAmount DECIMAL(12,2)
);

INSERT INTO #data(RowID, EmployeeID, AllowancePlan, FromDate, ToDate, AllowanceAmount)
VALUES
(1,200690,'CarAllowance','30/03/2017', NULL, 1000.0),
(2,200690,'CarAllowance','01/08/2017', NULL, 1000.0),
(6,200690,'CarAllowance','23/04/2018', NULL, 1000.0),
(7,200690,'CarAllowance','30/03/2018', NULL, 1000.0),
(8,200690,'CarAllowance','21/06/2018', '01/04/2019', 1000.0),
(9,200690,'CarAllowance','04/11/2021', NULL, 1000.0),
(10,200690,'CarAllowance','30/03/2017', '13/05/2022', 1000.0),
(11,200690,'CarAllowance','14/05/2022', NULL, 850.0);

-- find where the break points are
WITH chg AS 
(
    SELECT *, 
        CASE WHEN LAG(EmployeeID, 1, -1) OVER(ORDER BY RowID) != EmployeeID
               OR LAG(AllowancePlan, 1, 'X') OVER(ORDER BY RowID) != AllowancePlan  
               OR LAG(AllowanceAmount, 1, -1) OVER(ORDER BY RowID) != AllowanceAmount
               OR LAG(ToDate, 1) OVER(ORDER BY RowID) IS NOT NULL
    THEN 1 ELSE 0 END AS NewGroup
    FROM #data   
), 
-- count the number of break points as we go to group the related rows
grp AS
(
    SELECT chg.*,
        ISNULL(
            SUM(NewGroup) 
                OVER (ORDER BY RowID 
                      ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW),
              0) AS grpNum
    FROM chg
) 
SELECT  MIN(grp.RowID) AS RowID, 
        MAX(grp.EmployeeID) AS EmployeeID,      
        MAX(grp.AllowancePlan) AS AllowancePlan,
        MIN(grp.FromDate) AS FromDate, 
        MAX(grp.ToDate) AS ToDate,  
        MAX(grp.AllowanceAmount) AS AllowanceAmount
FROM grp
GROUP BY grpNum

Answer 2

一种方法是获取所有行的最后日期，然后对其进行分组

select min(t.RowID) as RowID,
       t.EmployeeID,
       min(t.AllowancePlan) as AllowancePlan,
       min(t.FromDate) as FromDate,
       max(t.ToDate) as ToDate,
       min(t.AllowanceAmount) as AllowanceAmount
from   ( select t.RowID,
                t.EmployeeID,
                t.FromDate,
                t.AllowancePlan,
                t.AllowanceAmount,
                case when t.ToDate is null then ( select top 1 t2.ToDate 
                                                  from   test t2
                                                  where  t2.EmployeeID = t.EmployeeID
                                                  and    t2.ToDate is not null
                                                  and    t2.FromDate > t.FromDate -- t2.RowID > t.RowID
                                                  order by t2.RowID, t2.FromDate 
                                                )
                     else t.ToDate
                end as todate     
         from   test t
       ) t

group by t.EmployeeID, t.ToDate
order by t.EmployeeID, min(t.RowID)

自己看和测试in this DBFiddle

结果是

RowID	EmployeeID	AllowancePlan	FromDate	ToDate	AllowanceAmount
1	200690	CarAllowance	2017-03-30	2019-04-01	1000
9	200690	CarAllowance	2021-11-04	2022-05-13	1000
11	200690	CarAllowance	2022-05-14	(null)	850

根据中断条件将多行折叠成一行

Collapse multiple rows into a single row based upon a break condition

sql

sql-server