SELECT CAST(Speicherdatum as DATE) as DAY, COUNT(*)  AS [QUANTITY] FROM _
  Pruefergebnisse  GROUP by CAST(Speicherdatum AS DATE)ORDER BY CAST( _
  Speicherdatum AS DATE)

SELECT DATEADD([DAY], DATEDIFF([DAY], 0, Speicherdatum), 0) AS DAY, COUNT(*) AS _
  QUANTITY FROM   Pruefergebnisse GROUP BY DATEADD([DAY], DATEDIFF([DAY], 0, _
  Speicherdatum), 0) ORDER BY DAY

Vielen Dank,

Michael