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10 rows affected
| time | device | max_value | diff |
|---|---|---|---|
| 2019-07-19 12:50:00 | a | 900 | 700 |
| 2019-07-19 12:50:00 | b | 300 | 135 |
| 2019-07-19 12:45:00 | b | 165 | null |
| 2019-07-19 12:39:00 | a | 200 | 160 |
| 2019-07-19 12:30:00 | a | 40 | null |