Mysql, timestamp and find extreme values

Question

Is it possible in mysql to find extremes values I have table with columns (timestamp, value) and I have to detect when values started to increased and decreased and notice that value.

I.e with this datas

2015-05-14 04:40:00, 1000
2015-05-14 05:20:00, 2000
2015-05-14 08:00:00, 2500
2015-05-14 08:20:00, 500
2015-05-14 09:10:00, 700
2015-05-14 10:20:00, 700
2015-05-14 11:40:00, 1300
2015-05-14 12:10:00, 1800
2015-05-14 12:40:00, 2700
2015-05-14 13:20:00, 3500
2015-05-14 14:10:00, 500
2015-05-14 14:30:00, 700
2015-05-14 14:50:00, 1000

I need to find 2015-05-14 08:00:00, 2500 as max and

2015-05-14 08:20:00, 500 as min and second point
2015-05-14 13:20:00, 3500 as max
2015-05-14 14:10:00, 500 as min

I want to find only extreme values so I need to find only rising and trailing edge.

Data are represented in that way http://fastwork.pl/karol/wykres_extrema.png

Answer 1

You can simply use MIN and MAX

SELECT *
FROM yourTable
WHERE value = (SELECT MIN(value)
               FROM yourTable);

And it works the same for MAX.

Answer 2

Not full answer. But for selecting only growing values you can use:

SELECT t2.val
FROM `test` t1
JOIN `test` t2 ON ( t1.id = t2.id -1
AND t1.val < t2.val ) 

You need to add id primary autoincrement field

Now you need to find hole in this data https://www.google.com/search?q=mysql+holes