T-SQL 透视行到列

Question

I am using SQL Server 2012 and have a table that has the following columns:

ID, Date, CustomFieldName, CustomFieldValue

The CustomFieldName column has 100 values (I know how stupid this sounds) but for the sake of simplicity lets say they are CustomField1, CustomField2, CustomField3

I would like to create a pivot where the out put looks like

ID, Date, CustomField1, CustomField2, CustomField3 where the Max date of CustomFieldVaue's is aggregated.

I have failed horribly in this, but have some progress (though my max isnt right and getting a lot of wrong data)

Any help would be appreciated!

SELECT [date],[id], [CustomField1], [CustomField2], [CustomField3]
from
(
  SELECT [date], [id], [CustomFieldValue], [CustomFieldName], 
    row_number() over(partition by [CustomFieldName] order by [CustomFieldValue]) rn
  from CustomTable
) as st
pivot
(
  max([CustomFieldValue])
  FOR [CustomFieldName] in ([CustomField1], CustomField2, [CustomField3])
) as pivottable
order by [id]

Answer 1

Hope I got it right, you want to pivot the rows (COlumnName1,2,...etc) as columns, so I've made a little script that's ready to run.

I recommend CTE's when it comes to pivoting, makes it easier, if you want to see the whole structure of the query just do a select @xSqlString

set nocount on;

create table 
    #testTable 
        (
            ID                  int identity(1,1),
            [Date]              datetime default getdate(),
            CustomFieldName     nvarchar(50),
            CustomFieldValue    date
        );

declare
    @i int = 0,
    @xSqlStringPivot  nvarchar(max) = '',
    @xSqlString       nvarchar(max) = '';

while(@i<=100)
begin

set
    @xSqlStringPivot += concat('CustomFieldName',cast(@i as nvarchar(50)),char(13), case when @i<100 then ', ' else '' end);

insert into #testTable
    (
        CustomFieldName,
        CustomFieldValue
    )
values
    (
        concat('CustomFieldName', cast(@i as nvarchar(50))),
        dateAdd(day,-@i,getdate())
    );

set
    @i += 1;

end;


select * from
    #testTable


set
    @xSqlString = 
        (
            'with ctePiv as
            (
            select
                t.CustomFieldName,
                t.CustomFieldValue
            from
                #testTable t
            )
            select
                *
            from
                ctePiv
            pivot
            (
                max(customFieldValue) for customFieldName in
                    (
                    '+ @xSqlStringPivot +'          
                    )
            )p'
        );

exec sp_executeSQL @xSqlString


drop table #testTable;

Edit 1

1. I am referencing the custom table on the while block, basically I'm iterating 100 times to populate the table with 100 rows. This is just to simulate your case.

   while(@i<=100) begin

   set @xSqlStringPivot += concat('CustomFieldName',cast(@i as nvarchar(50)),char(13), case when @i<100 then ', ' else '' end);

   insert into #testTable ( CustomFieldName, CustomFieldValue ) values ( concat('CustomFieldName', cast(@i as nvarchar(50))), dateAdd(day,-@i,getdate()) );

   set @i += 1;

   end;

2. @xSqlStringPivot is just a small trick to make a list of elements (CustomFieldName0, CustomFieldName1, etc) and to concatenate it to a dynamic SQL string, notice that I'm doing this in the while block, I just concatenate 'CustomField' with the current iteration number and with a carry feed (space).