Grouping over multiple data dimensions (pivot) I am logging an Events table, and want an output (as seen at the bottom of this answer), the issue is that I am getting the data in rows, but want them to be displayed column-wise.

The two dimensions are following:


Datetime values (per Day)
ServerId (per Server)


I think I have to group Datetime values by a time part (e.g. by minutes, or per hour) and retrieve a list of occourences of events per server, but I dont know how to write the query? Do I need a having by clause? 

I've already written the create statements, the structure is as following: 

CREATE TABLE [dbo].[events](
    [guidEventId] [uniqueidentifier] PRIMARY KEY,
    [dtStart] [datetime2](7) NOT NULL,
    [nDirection] [int] NOT NULL,
    [nServerId] [int] NOT NULL
) 

INSERT INTO events 
    ([guidEventId],[dtStart],[nDirection],[nServerId])
VALUES
    (newId(),'2013-08-01 00:01:00','0','1'),
    (newId(),'2013-08-01 00:02:00','1','1'),
    (newId(),'2013-08-01 00:03:00','0','1'),
    (newId(),'2013-08-01 00:04:00','1','2'),
    (newId(),'2013-08-02 00:01:00','0','1'),
    (newId(),'2013-08-02 00:02:00','1','2'),
    (newId(),'2013-08-02 00:03:00','0','2'),
    (newId(),'2013-08-02 00:04:00','1','2');


http://sqlfiddle.com/#!6/25e74

The end table should look something like that (daywise):

DateTime     | Server1 | Server2 |     Sum |
--------------------------------------------
2013-08-01   |       3 |       1 |       4 |
2013-08-02   |       1 |       3 |       4 |
The PIVOT operator may be of help. Take a look at Books Online

For example:

SELECT 
    DtStart AS Date, 
    ISNULL([1], 0) AS [Server 1], 
    ISNULL([2], 0) AS [Server 2], 
    ISNULL([3], 0) AS [Server 3]
FROM
(
    SELECT 
        DtStart, 
        nServerID, 
        NDirection 
    FROM dbo.events 
) AS SourceTable
PIVOT
(
    SUM(NDirection)
    FOR nServerID IN ([1], [2], [3])
) AS PivotTable
ORDER BY 
    DtStart ASC