Convert Columns to rows in SQL Server by using PIVOT

Question

I know, this question is not new and I read a lot of examples here, but couldn't find the solution for my task:

I have mainly two tables, related by 1:n. The TestPlan_Measure_Modules_Sensors which is a collection of sensor channels and the channels themselves in the table Machine_TestResults_Values.

The number of channels varies for each TestPlan_Measure_Modules_Sensors.

Here are the definitions:

The id_TestPlan_Measure_Module_Sensors is linked to the sensor definition.

Assuming, that the "Drehzahl" sensor has two values, a query results in following table:

SELECT        
    TestPlan_Measure_Module_Sensors.SensorName, LineNumber, Value
FROM
    Machine_TestResults_Sensors 
LEFT JOIN
    Machine_TestResults_Values ON Machine_TestResults_Sensors.id = Machine_TestResults_Values.id_Machine_TestResults_Sensors 
LEFT JOIN
    TestPlan_Measure_Module_Sensors ON Machine_TestResults_Sensors.id_TestPlan_Measure_Module_Sensors = TestPlan_Measure_Module_Sensors.id 
WHERE 
    id_Machine_Measure_Modules = 253

Now I need to switch rows and columns to get an output like this:

I assume I need dynamic SQL to achieve results based on the variable number of columns and a proper Pivot statement. But Pivot in SQL Server is not really my strength, so I hope someone here can hep me.

UPDATE: Thx to the hint, I tried the solution SQL Server dynamic PIVOT query?

My example, adjusted to solution in above link, results in following table:

Any idea how to get rid of the first 'NULL' line ?

UPDATE: I added a DELETE statement into the query, now it looks like it should.

Here is my version of the query:

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


SELECT        
    TestPlan_Measure_Module_Sensors.SensorName, LineNumber, Value
FROM
    Machine_TestResults_Sensors 
LEFT JOIN
    Machine_TestResults_Values ON Machine_TestResults_Sensors.id = Machine_TestResults_Values.id_Machine_TestResults_Sensors 
LEFT JOIN
    TestPlan_Measure_Module_Sensors ON Machine_TestResults_Sensors.id_TestPlan_Measure_Module_Sensors = TestPlan_Measure_Module_Sensors.id 
WHERE 
    id_Machine_Measure_Modules = 253

SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.SensorName) 
        FROM #temp c
        FOR XML PATH(''), TYPE
        ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

SET @query = 'SELECT LineNumber, ' + @cols + ' INTO #pt from 
        (
            select LineNumber,
                    [Value],
                    SensorName
            from #temp
       ) x
        pivot 
        (
             max([Value])
            for SensorName in (' + @cols + ')
        ) p; DELETE FROM #pt WHERE LineNumber IS NULL; SELECT * FROM #pt;'

Execute(@query);

DROP TABLE #temp