Dynamically select distinct current and previous columns from a sql table

Question

I have a temporary table like so

   Id  |Name    |Status |   Rate |  Method  |ModifiedTime             |ModifiedBy
------------------------------------------         


        

Answer 1

Assuming NAME (Recipe1) is a key

Declare @Table table (Id int,Name varchar(50),Status int,Rate int,Method varchar(50),ModifiedTime DateTime,ModifiedBy varchar(50))
Insert Into @Table values
(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')

Declare @XML xml
Set @XML = (Select * from @Table for XML RAW)

;with cteBase as (
    Select ID           = r.value('@Id','int') 
          ,Name         = r.value('@Name','varchar(150)')
          ,ModifiedTime = r.value('@ModifiedTime','varchar(150)')
          ,ModifiedBy   = r.value('@ModifiedBy','varchar(150)')
          ,Item         = Attr.value('local-name(.)','varchar(max)')
          ,Value        = Attr.value('.','varchar(max)')
    From  @XML.nodes('/row') AS A(r)
    Cross Apply A.r.nodes('./@*[local-name(.)!="Id"]') AS B(Attr)
)
,cteExt as (Select *,LastValue =Lag(Value) over (Partition By Name,Item Order by ModifiedTime) From cteBase)
Select Name
      ,Item
      ,Before=LastValue
      ,After =Value
      ,ModifiedTime
      ,ModifiedBy
 From  cteExt 
 Where Value<>LastValue and LastValue is not null
   and Item not in ('ModifiedTime','ModifiedBy')
 Order By Name,ModifiedTime

Returns

Name    Item    Before  After   ModifiedTime            ModifiedBy
Recipe1 Method  xyz     abc     2016-07-26T14:56:18.123 A
Recipe1 Method  abc     xyz     2016-07-26T14:57:50.180 b
Recipe1 Status  0       1       2016-07-26T14:57:50.180 b