如何按照下面的要求从 SQL 服务器中检索数据？

Question

我有一个这样的 table :

  CustName    Country    RecordedTime
 ---------------------------------------------
  Alex        Australia  2018-Jun-01 08:00 AM
  Alex        China      2018-Jun-01 10:00 AM
  Alex        Japan      2018-Jun-01 11:00 AM
  John        Australia  2018-Jun-01 08:00 AM
  John        China      2018-Jun-02 08:00 AM
  Bob         Australia  2018-Jun-02 09:00 AM
  Bob         Brazil     2018-Jun-03 09:50 AM

如果记录在系统中是全新的，那么它应该在给定日期的审计和历史字段（结果集中的两个附加字段）中显示 'ADD' & 'NEW'。

如果记录在那天被编辑了两次，那么它应该在审计字段中显示 'ADD' 和 'CHANGE ' 以及在历史状态字段中显示 'BEFORE' 和 'CURRENT' 的两个条目分别针对给定的日期。

例如，我的结果应该是这样的；

当我将输入日期传递为 2018-Jun-01 时，输出应如下所示：

   CustName    Country    RecordedTime           Audit    History
  ----------------------------------------------------------------
   Alex        Australia  2018-Jun-01 08:00 AM   ADD      NEW
   Alex        China      2018-Jun-01 10:00 AM   CHANGE   BEFORE
   Alex        Japan      2018-Jun-01 11:00 AM   CHANGE   CURRENT
   John        Australia  2018-Jun-01 08:00 AM   ADD      NEW

当我将输入日期传递为 2018-Jun-02 时，输出应如下所示：

   CustName    Country    RecordedTime           Audit    History
  -----------------------------------------------------------------
   John        China      2018-Jun-02 08:00 AM   CHANGE   CURRENT
   Bob         Australia  2018-Jun-02 09:00 AM   ADD      NEW

当我将输入日期传递为 2018-Jun-02 时，输出应如下所示：

   CustName    Country    RecordedTime           Audit    History
  ----------------------------------------------------------------
   Bob         Brazil     2018-Jun-03 09:50 AM   CHANGE   CURRENT

我尝试了很多方法，但仍然缺少一些实现此目的的方案。有人可以解释一下吗？

Answer 1

一种方法是通过如下所示的 cte，其中我们有 row_number() 函数来双向跟踪序列。

见live demo

; with cte as 
(
select *, rn= row_number() over(partition by CustName order by RecordedTime),
rn2=row_number() over(partition by CustName order by RecordedTime desc)
from records
    )
, cte2 as
(
select *, audit='New', History='Change' from cte where rn=1
    union 
select *, audit='Change', History='Current' from cte where rn2=1 and rn<>1
    union
select *, audit='Change', History='before' from cte where rn>1 and rn2<>1
)

select 
    CustName,
    Country,
    RecordedTime,
    audit,
    History
from cte2
order by  CustName,RecordedTime

Answer 2

我会简单地使用 case 表达式。

select t.*,
       (case when seqnum = 1 then 'ADD' else 'CHANGE' end) as audit,
       (case when seqnum = 1 then 'NEW'
             when seqnum_day = 1 then 'CURRENT'
             else 'BEFORE'
        end) as history
from (select t.*,
             row_number() over (partition by custname order by recordedtime) as seqnum,
             row_number() over (partition by custname, cast(recordedtime as date) order by recordedtime desc) as seqnum_day
      from t
     ) t;

sqlfiddle:http://sqlfiddle.com/#!18/43c08/27

Answer 3

你可以试试

CASE WHEN 和 RANK 与 Windows 函数

;WITH CTE (CustName,Country,RecordedTime,rn) AS(
  SELECT *,RANK() OVER(PARTITION BY CustName ORDER BY RecordedTime) rn
  FROM T
)
SELECT t.*,
       (CASE WHEN rn = 1 then 'ADD' ELSE 'CHANGE' END) 'Audit',
       (CASE 
          WHEN rn = 1  then 'NEW'
          WHEN t2.mRn = rn then 'CURRENT' 
       ELSE 'BEFORE' END) 'History'
FROM CTE t LEFT JOIN  (
  SELECT MAX(rn) mRn,CustName  FROM CTE GROUP BY CustName
) t2 on t2.mRn = t.rn and t2.CustName = t.CustName
WHERE CONVERT(char(10), RecordedTime,126) = '2018-06-02'

sqlfiddle:http://sqlfiddle.com/#!18/43c08/26

如何按照下面的要求从 SQL 服务器中检索数据？

How to retrieve data from SQL Server as required below?

sql

tsql

sql-server

sql-server-2008

ssms-2014