Helo,this is my query:
MariaDB [PV_Anlage]>
SELECT created_at, verbrauch_ges FROM pv_metrics group by DATE(created_at) ORDER BY ID DESC limit 20;+---------------------+---------------+| created_at | verbrauch_ges |+---------------------+---------------+| 2025-03-23 00:00:04 | 5628.79 || 2025-03-22 00:00:06 | 5622.54 || 2025-03-21 00:00:11 | 5615.44 || 2025-03-20 00:00:13 | 5609.49 || 2025-03-19 00:00:17 | 5605.4 || 2025-03-18 00:00:00 | 5600.45 || 2025-03-17 00:00:03 | 5591.36 || 2025-03-16 00:00:09 | 5585.2 || 2025-03-15 00:00:16 | 5578.96 || 2025-03-14 00:00:04 | 5571.1 || 2025-03-13 00:00:07 | 5560.34 || 2025-03-12 00:00:10 | 5550.54 || 2025-03-11 00:00:13 | 5540.12 || 2025-03-10 00:00:16 | 5534.81 || 2025-03-09 00:00:18 | 5528.48 || 2025-03-08 00:00:17 | 5521.71 || 2025-03-07 00:00:11 | 5515.27 || 2025-03-06 00:00:14 | 5510.17 || 2025-03-05 00:00:06 | 5504.08 || 2025-03-04 00:00:09 | 5497.21 |+---------------------+---------------+This is the result, as I'm writing values every 20sec. I've selected the very firste value of the day, so now I need the diffrence between the days. I've tried with LAG() function but I dont understand how to include the function into the general query.
best regardasFrank