Menghitung nilai rata-rata selama bagian tanggal/waktu

SELECT  DAY(Timestamp), HOUR(Timestamp), MINUTE(Timestamp), AVG(value)
FROM    mytable
GROUP BY
        DAY(Timestamp), HOUR(Timestamp), MINUTE(Timestamp) WITH ROLLUP

WITH ROLLUP klausa di sini menghasilkan baris tambahan dengan rata-rata untuk setiap HOUR dan DAY , seperti ini:

SELECT  DAY(ts), HOUR(ts), MINUTE(ts), COUNT(*)
FROM    (
        SELECT  CAST('2009-06-02 20:00:00' AS DATETIME) AS ts
        UNION ALL
        SELECT  CAST('2009-06-02 20:30:00' AS DATETIME) AS ts
        UNION ALL
        SELECT  CAST('2009-06-02 21:30:00' AS DATETIME) AS ts
        UNION ALL
        SELECT  CAST('2009-06-03 21:30:00' AS DATETIME) AS ts
        ) q
GROUP BY
        DAY(ts), HOUR(ts), MINUTE(ts) WITH ROLLUP

2, 20, 0, 1
2, 20, 30, 1
2, 20, NULL, 2
2, 21, 30, 1
2, 21, NULL, 1
2, NULL, NULL, 3
3, 21, 30, 1
3, 21, NULL, 1
3, NULL, NULL, 1
NULL, NULL, NULL, 4

2, 20, NULL, 2 di sini berarti COUNT(*) adalah 2 untuk DAY = 2 , HOUR = 20 dan semua menit.