Question

I have a table that looks like

Customer_id     Order_id   Action    Time_Stamp
abc             123         placed     8/1/2012 10:00AM
abc             123         processed  8/1/2012 10:30AM
abc             123         shipped    8/1/2012 11:00AM

xyz             456         recieved   8/1/12 12:00PM 

what i am trying to get is

Customer ID     Order_id   Placed             Processed           Shipped            recieved
abc              123       8/1/2012 10:00Am    8/1/2012 10:30AM   8/1/2012 11:00AM   null
xyz              456       null                null               null               8/1/2012 12:00PM

i know the max number of columns i would need (the number of actions in other words) if that makes the query easier.

any help is much appreciated.

Answer 1

You can use a PIVOT for this type of query.

SELECT *
FROM 
(
    SELECT Customer_id, Order_id, Action, Time_Stamp
    FROM yourTable
) x
PIVOT
(
   max(Time_Stamp)
   for action in ([Placed], [Processed], [Shipped], [received])
) p

See SQL Fiddle with Demo

The above query works great if you know the values of the columns you want to create. But if you do not, then you can use a dynamic pivot:

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(action) 
                    from test
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')


set @query 
      = 'SELECT Customer_id, Order_id,' + @cols + ' from 
         (
            select Customer_id, Order_id, Action, Time_Stamp
            from test
         ) x
         pivot 
         (
            max(Time_Stamp)
             for action in(' + @cols + ')
         ) p '

execute(@query)

See SQL Fiddle with Demo