Select 分钟 BeginDate 从重复

Question

select [BK_Vendedor]
       ,[NIF]
      ,[BeginDate]
      ,[EndDate]
from (
      select 
       [BK_Vendedor]
      ,[NIF]
      ,[BeginDate]
      ,[EndDate],
             count(*) over (partition by [BK_Vendedor]) as dc
      from [test_SA].[dbo].[Dim_Vendedor]
     ) as T
where dc > 1

此 table 是此查询的结果，该查询仅从另一个更大的 table 的 BK_Vendedor 列中选取重复值。但在同一个查询中，我也只想要每个 BK_Vendedor 中具有最小 BeginDate 的行。我该怎么做？

Answer 1

添加 ROW_NUMBER 在 BK_Vendedor 上分区并过滤行号 = 1。当您按字段（或多个字段！）分区 ROW_NUMBER 时，它会重置计数每次字段更改时都为 1。您有效地按字段分组，每个组都有自己的一系列行号。我们用它来获得每个组中的第一个 BeginDate。

请注意，如果我们想要 last BeginDate 我们将反转顺序，因此最后一个是 #1 (ROW_NUMBER () over (partition by BK_Vendedor ORDER BY BeginDate DESC) as Ord) 并保留 WHERE 子句指定 Ord = 1

with cteSampleData as (
    SELECT * FROM (VALUES (100, 10, '2022-01-10', '2022-01-25') 
        , (100, 10, '2022-01-08', '2022-01-15') 
        , (101, 11, '2022-03-10', '2022-04-15') 
        , (102, 12, '2022-02-10', NULL) 
        , (103, 13, '2022-02-15', NULL) 
        , (103, 13, '2022-03-15', '2022-04-10') 
        , (103, 15, '2022-02-21', '2022-04-01') --EDIT: Add this row
    ) as DimVend(BK_Vendedor,NIF,BeginDate,EndDate)
) --The above is just sample data as I don't have your [test_SA].[dbo].[Dim_Vendedor]
select [BK_Vendedor]
       ,[NIF]
      ,[BeginDate]
      ,[EndDate]
from (
      select 
       [BK_Vendedor]
      ,[NIF]
      ,[BeginDate]
      ,[EndDate],
             count(*) over (partition by [BK_Vendedor]) as dc
             --Add the line below
             , ROW_NUMBER () over (partition by BK_Vendedor ORDER BY BeginDate) as Ord
      from cteSampleData
     ) as T
where dc > 1
    AND Ord = 1 --And add this line too

输入如下所示：

BK_Vendedor	NIF	BeginDate	EndDate
100	10	2022-01-10	2022-01-25
100	10	2022-01-08	2022-01-15
101	11	2022-03-10	2022-04-15
102	12	2022-02-10	NULL
103	13	2022-02-15	NULL
103	13	2022-03-15	2022-04-10

输入（按原始顺序）加上 dc 和 Ord：

BK_Vendedor	NIF	BeginDate	EndDate	dc	Ord
100	10	2022-01-10	2022-01-25	2	2
100	10	2022-01-08	2022-01-15	2	1
101	11	2022-03-10	2022-04-15	1	1
102	12	2022-02-10	NULL	1	1
103	13	2022-02-15	NULL	3	1
103	13	2022-03-15	2022-04-10	3	3
103	15	2022-02-21	2022-04-01	3	2

输出如下所示：

BK_Vendedor	NIF	BeginDate	EndDate
100	10	2022-01-08	2022-01-15
103	13	2022-02-15	NULL

Select 分钟 BeginDate 从重复

Select min BeginDate from duplicates

sql-server

min

duplicates

partition-by