I have a table like this:
ID | Type | Value | Timestamp
--------------------------------
1 | AAA | 0.5 | day 1 hour 1
2 | BBB | 1.5 | day 1 hour 1
3 | CCC | 1.8 | day 1 hour 1
.....
11 | AAA | 0.6 | day 1 hour 2
12 | BBB | 1.4 | day 1 hour 2
13 | CCC | 1.5 | day 1 hour 2
.....
ID := Int, PK, AI, and so on
Type := String/Varchar
Value := Double
Timestamp := Unix Timestamp (Int), could be easily changed to date type
What I want is now an average for specific timeframes. For example:
I want all AAA and all BBB with an average of "Value" for day 1 till day 3. Every day has 24 entries per type over several days.
Expected result would be
Type | Average | Timestamp/Date
-------------------------------
AAA | 0.5242 | Day 1
AAA | 0.5442 | Day 2
AAA | 0.5913 | Day 3
BBB | 1.4228 | Day 1
BBB | 1.6924 | Day 2
BBB | 1.3018 | Day 3
I'm not sure if this is possible just with mysql. Maybe it's more efficient to do it with PHP?
Does this produce the result you require?
# DROP TABLE IF EXISTS likeThis;
CREATE TABLE likeThis (id INT UNSIGNED, `type` CHAR(255), `value` DECIMAL(2,1), `timestamp` CHAR(255));
INSERT INTO likeThis VALUES
(1, 'AAA', 0.5, 'day 1 hour 1'),
(2, 'BBB', 1.5, 'day 1 hour 1'),
(3, 'CCC', 1.8, 'day 1 hour 1'),
(11, 'AAA', 0.6, 'day 1 hour 2'),
(12, 'BBB', 1.4, 'day 1 hour 2'),
(13, 'CCC', 1.5, 'day 1 hour 2');
SELECT * FROM likeThis;
SELECT type, AVG(`value`) average, LEFT(`timestamp`, INSTR(`timestamp`, 'hour') - 2) timestampDate FROM likeThis GROUP BY `type`, LEFT(`timestamp`, INSTR(`timestamp`, 'hour') - 2);
Let me know if not,
Regarding how to adapt the query if the date is stored in differing field types, here are some example queries:
# How to aggregate by day on a DATETIME field type timestamp
SELECT type, AVG(`value`) average, DATE_FORMAT(`timestamp`, '%Y%m%d') timestampDate FROM likeThis GROUP BY `type`, DATE_FORMAT(`timestamp`, '%Y%m%d');
# How to aggregate by day on a unix timestamp (stored as INT) field type timestamp
SELECT type, AVG(`value`) average, `timestamp` - `timestamp` % 86400 timestampDate FROM likeThis GROUP BY `type`, `timestamp` - `timestamp` % 86400;
Thanks,
James