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我有一個帶有工作站,工作站和會話的數據庫。會話描述哪個工作人員在哪個工作站上。我設法建立一個查詢,給我每個會話重疊的持續時間。MySQL中2個外鍵的每個組合的重疊持續時間之和
SELECT
sA.station_id,
sA.worker_id AS worker1,
sB.worker_id AS worker2,
SEC_TO_TIME(
TIME_TO_SEC(LEAST(sA.end,sB.end)) - TIME_TO_SEC(GREATEST(sA.start,sB.start))
) AS overlap
FROM
`sessions` AS sA,
`sessions` AS sB
WHERE
sA.station_id = sb.station_id
AND
sA.station_id = 6
AND (
sA.start BETWEEN sB.start AND sB.end
OR
sA.end BETWEEN sB.start AND sB.end
)
與此查詢我得到的結果是這樣
station_id worker1 worker2 overlap
6 1 1 09:00:00
6 2 1 02:30:00
6 5 1 00:00:00
6 1 1 09:00:00
6 2 1 01:30:00
6 3 1 09:00:00
...
6 12 3 02:00:00
6 14 3 01:00:00
6 17 3 02:00:00
...
我現在想就是總結重疊的worker1和worker2的每個組合,以獲得整體重疊的時間。
我試過使用SUM()和GROUP BY的不同方式,但我從來沒有得到想要的結果。
SELECT
...
SEC_TO_TIME(
**SUM**(TIME_TO_SEC(LEAST(sA.end,sB.end)) - TIME_TO_SEC(GREATEST(sA.start,sB.start)))
) AS overlap
...
#has as result
station_id worker1 worker2 overlap
6 1 1 838:59:59
#in combination with
GROUP BY
worker1
#i get
station_id worker1 worker2 overlap
6 1 1 532:30:00
6 2 1 -33:00:00
6 3 1 270:30:00
6 5 1 598:30:00
6 6 1 542:00:00
6 7 1 508:00:00
6 8 5 53:00:00
6 9 1 54:30:00
6 10 1 310:00:00
6 11 1 -108:00:00
6 12 1 593:30:00
6 14 1 97:30:00
6 15 1 -53:30:00
6 17 1 293:30:00
最後的結果是接近,但我仍然缺少很多組合。我也不明白爲什麼會顯示組合8 - 5。
感謝烏拉圭回合的幫助(和時間來讀)