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sql - Sql查询以获取基于月份的唯一日期

问题描述

我正在从表中提取一些数据。

declare @SampleData as Table(Id int, ContactId int, Item varchar(25),CreatedOn date)

insert into @SampleData
VALUES(100,2500,'Some item name 1212', '9/5/2020'),
      (104,2500,'Some item name 2232', '9/15/2020'),
      (109,2500,'Some item name 3434', '9/20/2020'),

      (112,3000,'Some item name 5422', '8/1/2020'),
      (132,3000,'Some item name 344', '9/5/2020'),
      (134,3000,'Some item name 454', '9/15/2020'),

      (139,3500,'Some item name 6455', '7/5/2020'),
      (146,3500,'Some item name 546', '8/5/2020'),
      (142,3500,'Some item name 867', '9/5/2020'),
      (149,3500,'Some item name 677', '9/15/2020'),
      (150,3500,'Some item name 888', '9/19/2020')

这里的逻辑是让您每个月都可以找到新的联系人 ID（所以逻辑是如果同一联系人在该月 1 日的最后 28 天内没有任何记录，则视为新联系人）

当您有两个日期期间时，这很容易做到，因此您可以排除您想要的记录，如下所示

SELECT *
FROM @SampleData
WHERE CreatedOn> = @FromDate
    and CreatedOn <=@Date
    and ContactId not in (SELECT ContactId
                          FROM @SampleData
                          WHERE CreatedOn >= DateAdd(Day, -28,@FromDate)
                            AND CreatedOn < @FromDate)

我想要的是在没有参数的情况下预先填充这些数据，以便用户可以使用。

在此示例数据中，我预计 7 月的联系人为 3500，8 月的联系人为 3000，9 月的联系人为 2500&3000。

此外，它只需要显示每个联系人的记录而不是重复的。

DECLARE @From date,
        @To date
DECLARE date_cursor CURSOR FOR 
select distinct DATEADD(month, DATEDIFF(month, 0, CreatedOn), 0) FromDate,EOMONTH(CreatedOn) ToDate
from @SampleData

OPEN date_cursor  
FETCH NEXT FROM date_cursor INTO @From,@To  

WHILE @@FETCH_STATUS = 0  
BEGIN  

     SELECT *
     FROM (
             SELECT DISTINCT ContactId,@From 'From Date', @To 'To Date'
             FROM @SampleData D
             WHERE D.CreatedOn>= @From AND D.CreatedOn <= @To
                AND  ContactId NOT IN (SELECT ContactId
                                  FROM @SampleData
                                  WHERE CreatedOn >= DateAdd(Day, -28,@From)
                                    AND CreatedOn < @From)) ContactData
                    OUTER APPLY (
                            --pick first row for the contact as per the period
                            SELECT TOP 1 *
                            FROM @SampleData D
                            WHERE D.ContactId = ContactData.ContactId
                                AND D.CreatedOn >= ContactData.[From Date]
                                AND D.CreatedOn < ContactData.[To Date]
                            ORDER BY CreatedOn 
                            ) Records


      FETCH NEXT FROM date_cursor INTO  @From,@To   
END 

CLOSE date_cursor  
DEALLOCATE date_cursor

结果

ContactId   From Date   To Date     Id  Item                 CreatedOn
3500       01/07/2020   31/07/2020  139 Some item name 6455 05/07/2020
3000       01/08/2020   31/08/2020  112 Some item name 5422 01/08/2020
2500       01/09/2020   30/09/2020  100 Some item name 1212 05/09/2020
3000       01/09/2020   30/09/2020  132 Some item name 344  05/09/2020

我想摆脱光标，有没有可能

标签： sqlsql-serversql-server-2016

解决方案

lag()您可以通过使用和比较行来为联系人分配分组：

select sd.*,
       sum(case when prev_createdon > dateadd(day, -28, createdon) then 0 else 1 end) over
           (partition by contactid order by createdon) as grouping
from (select sd.*,
             lag(createdon) over (partition by contactid order by createdon) as prev_createdon
      from SampleData sd
     ) sd;

如果您只想要一系列相邻记录中的第一行，那么：

select sd.*
from (select sd.*,
             lag(createdon) over (partition by contactid order by createdon) as prev_createdon
      from SampleData sd
     ) sd
where prev_createdon < dateadd(day, -28, createdon) or prev_createdon is null;

这是一个 db<>fiddle。

编辑：

根据修改后的问题，您要按组进行总结。您可以使用：

select contactid, min(createdon), max(createdon), min(id),
       max(case when seqnum = 1 then item end) as item
from (select sd.*,
             row_number() over (partition by contactid, grouping order by createdon) as seqnum
      from (select sd.*,
                   sum(case when prev_createdon > dateadd(day, -28, createdon) then 0 else 1 end) over
                        (partition by contactid order by createdon) as grouping
            from (select sd.*,
                         lag(createdon) over (partition by contactid order by createdon) as prev_createdon
                  from SampleData sd
                 ) sd
           ) sd
     ) sd
group by contactid, grouping;

我也更新了数据库小提琴以拥有它。

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