mysql - wie Zeitdifferenz zu finden, basierend auf hoch zu niedrig erreichte Zeit

Question

Ich habe eine Tabelle Water_Tank genannt,

select * from tank_id; 


id unique_tankId highLevel lowLevel 
1  1    75   50 
2  2    80   55 


select * from water_tank where tabkId=1; 


id tankId level serverTimeStamp 
1  1  50  2016-06-28 12:00:01 
2  1  60  2016-06-28 12:59:01 
3  1  85  2016-06-28 13:00:01 
4  1  89  2016-06-28 13:30:01 
5  1  90  2016-06-28 14:00:01 
6  1  100  2016-06-28 15:00:01 
7  1  10  2016-06-28 16:00:01 
8  1  20  2016-06-28 16:30:01 
9  1  28  2016-06-28 17:00:01 
10 1  50  2016-06-29 12:00:01 
11 1  60  2016-06-29 12:59:01 
12 1  67  2016-06-29 13:00:01 
13 1  75  2016-06-29 15:00:01 
14 1  90  2016-06-29 16:00:01 
15 1  95  2016-06-29 17:00:01 
16 1  98  2016-06-29 18:00:01 
17 1  100  2016-06-29 19:30:01 
18 1  24  2016-06-29 20:00:01 
..  .. ..  ... 
..  .. ..  ... 

Hinweis: id ist AI und tankId ist Fremdschlüssel

Ich möchte finde den Zeitunterschied von high (level> = 75) level serverTimeStamp zu low (level < 50) level serverTimeStamp mit mysql query.

Erwartet Ausgabe:

timeDiffInHour  highReachedTime   cleanedTime 
3     2016-06-28 13:00:01  2016-06-28 16:00:01 
5     2016-06-29 15:30:01  2016-06-29 20:00:01 
..     ...      ... 

Jemand mir helfen, dies zu erreichen?

Answer 1

Vielleicht so etwas?

SELECT tankId, 
MIN(serverTimeStamp) lowReachedTime, 
b.highReachedTime, 
TIMESTAMPDIFF(HOUR,MIN(serverTimeStamp),b.highReachedTime) timeDiffinHour 
FROM tankId a 
INNER JOIN (
    SELECT tankId, MAX(serverTimeStamp) highReachedTime 
    FROM water_tank 
    WHERE level > 75 
    GROUP BY tankId 
) b ON b.tankId = a.tankId 
WHERE level < 50 
GROUP BY a.tankId