从 sql 表中选择不同的当前和以前的列

Select distinct current and previous columns from a sql table(从 sql 表中选择不同的当前和以前的列)

问题描述

我有一张这样的桌子

   Id  |Name    |Status |   Rate |  Method  |ModifiedTime             |ModifiedBy
-----------------------------------------------------------------------------
    1  |Recipe1 |  0    |    30  |   xyz    | 2016-07-26 14:55:57.977 |     A
-------------------------------------------------------------------------------
    2  |Recipe1 |  0    |    30  |   abc    | 2016-07-26 14:56:18.123 |     A
--------------------------------------------------------------------------------
    3  |Recipe1 |  1    |    30  |   xyz    | 2016-07-26 14:57:50.180 |     b

我想只选择更改，并想显示以前的值是什么以及它当前伴随着什么以及谁更改了它.最终结果如下.我正在使用 SQL Server 2014.

I would like to select only the changes and wanted to show what the value was previously and what it is currently accompanied by who changed it. The final outcome will be as follows. I am using SQL Server 2014.

Item    | Before |  After |ModifiedTime             | ModifiedBy
-----------------------------------------------------------------------------
Method  |  xyz   |  Abc   | 2016-07-26 14:56:18.123 |   A
-------------------------------------------------------------------------------
Status  |  0     |  1     | 2016-07-26 14:57:50.180 |   b
--------------------------------------------------------------------------------
Method  |  Abc   |  xyz   | 2016-07-26 14:57:50.180 |   b

推荐答案

没有动态 SQL 这是我能做的最好的.我假设您按 Name 对更改进行分组.如果 Name 可以更改，则应将其从分区中删除并添加到项目子查询和 case 中.你可以试试这里

without dynamic SQL this is the best I could do. I'm assuming that you are grouping changes by Name. If Name can change it should be removed of the partition by and added to the items subquery and to the case. You can try it here

select item, 
       case item
         when 'Status' then cast(prevStatus as varchar)
         when 'Rate' then cast(prevRate as varchar)
         when 'Method' then prevMethod
         end as Before, 
       case item
         when 'Status' then cast(Status as varchar)
         when 'Rate' then cast(Rate as varchar)
         when 'Method' then Method
         end as After,
         ModifiedTime,
         ModifiedBy
  from (
    select Status,
           lag(Status) over (partition by Name order by id) prevStatus,
           Rate,
           lag(Rate) over (partition by Name order by id) prevRate,
           Method,
           lag(Method) over (partition by Name order by id) prevMethod,
           ModifiedBy,
           ModifiedTime
      from t ) as t1 cross join  (select 'Status' as item union all 
                                  select 'Rate' as item union all 
                                  select 'Method' as item) items
where (item = 'Status' and Status <> prevStatus)
   or (item = 'Rate' and Rate <> prevRate)
   or (item = 'Method' and Method <> prevMethod)
order by ModifiedTime

输出

item   Before After ModifiedTime            ModifiedBy 
------ ------ ----- ----------------------- ---------- 
Method xyz    abc   2016-07-26 14:56:18.123 A          
Status 0      1     2016-07-26 14:57:50.180 b          
Method abc    xyz   2016-07-26 14:57:50.180 b   

   

在第二行，您会看到 ModifiedBy 是 b，而您有 A.我认为是一个错字.

On the second row you'll see that ModifiedBy is b while you have A. I think is a typo.

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