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

Ok, I adapted my previous answer but on Dynamic SQL. It's a little crazy but it works (using testTable as table name you can change that just replace 'testTable'):

DECLARE @query NVARCHAR(max) 

SET @query = 'select item, case item'; 

SELECT @query = @query + Stuff(( SELECT 
' when '''+a.NAME+''' then cast(prev'+a.NAME+' as varchar) ' 
FROM sys.all_columns a JOIN sys.tables t ON 
t.object_id = a.object_id AND t.NAME = 'testTable' AND a.NAME 
NOT IN ('id', 
'Name', 'ModifiedTime', 'ModifiedBy') FOR xml path('') ), 1, 0, 
''); 

SET @query = @query + ' end as Before, case item '; 

SELECT @query = @query + Stuff(( SELECT 
                       ' when '''+a.NAME+''' then cast('+a.NAME+' as varchar) ' 
                       FROM sys.all_columns a JOIN sys.tables t ON t.object_id = 
                       a.object_id AND t.NAME = 'testTable' AND a.NAME NOT IN ( 
                'id', 
                       'Name', 
                       'ModifiedTime', 'ModifiedBy') FOR xml path('') ), 1, 1, 
                ''); 

SET @query = @query 
             + ' end as After, ModifiedTime, ModifiedBy from ( select '; 

SELECT @query = @query + Stuff(( SELECT a.NAME +', lag('+ a.NAME + 
                       ') over (partition by Name order by id) prev'+a.NAME+', ' 
                FROM 
                       sys.all_columns a JOIN sys.tables t ON t.object_id = 
                a.object_id 
                       AND t.NAME = 'testTable' AND a.NAME NOT IN ('id', 'Name', 
                       'ModifiedTime', 'ModifiedBy') FOR xml path('') ), 1, 0, 
                ''); 

SET @query = @query 
             + '  ModifiedBy, ModifiedTime from testTable ) as t1 cross join  (' 
; 

SELECT @query = @query + Stuff(( SELECT ' select '''+ a.NAME + 
                '''as item union all ' 
                       FROM 
                       sys.all_columns a JOIN sys.tables t ON t.object_id = 
                a.object_id 
                       AND t.NAME = 
                       'testTable' AND a.NAME NOT IN ('id', 'Name', 
                'ModifiedTime', 
                       'ModifiedBy') FOR xml path('') ), 1, 1, ''); 

SET @query = LEFT(@query, Len(@query) - 10); --get rid of last union all 
SET @query = @query + ' ) items where '; 

SELECT @query = @query + Stuff(( SELECT ' or (item = '''+ a.NAME +''' and '+ 
                a.NAME + 
                       ' !=  prev'+ a.NAME +')' FROM sys.all_columns a JOIN 
                sys.tables 
                       t ON t.object_id = a.object_id AND t.NAME = 'testTable' 
                AND 
                       a.NAME NOT IN ('id', 'Name', 'ModifiedTime', 'ModifiedBy' 
                ) FOR 
                       xml 
                       path('') ), 1, 3, ''); 

SET @query = @query + ' order by ModifiedTime'; 

EXECUTE Sp_executesql 
  @query