SET NOCOUNT ON;
GO

DECLARE @DataDa datetime;
DECLARE @DataA datetime;

SELECT @DataDa = GETDATE();
SELECT @DataDa;


INSERT INTO dbo.Risultati (idTestata, valore)
SELECT
    T.idTestata
  , MAX(CASE 
      WHEN (DATEPART(minute, dataDettaglio) % 2) <> 0 
      THEN valoreInt / valoreDec
      ELSE 999
    END)
FROM
  dbo.Testata        T
  JOIN dbo.Dettagli    D ON D.idTestata = T.idTestata
WHERE
  T.idTestata <= 100
GROUP BY
  T.idTestata
    
SELECT @DataA = GETDATE();
SELECT @DataA;

PRINT 'durata totale: ' + CAST(DATEDIFF(millisecond, @DataDa, @DataA) * 1.0 AS varchar(20)) + ' millisec.';

DELETE FROM dbo.Risultati;

/*
-----------------------
2013-10-03 18:43:00.880

-----------------------
2013-10-03 18:43:00.917

durata totale: 36.0 millisec.
*/