Periodi di tempo della query MySQL e valore della caduta massima rispetto al valore massimo precedente

Sospetto che possano essere ottimizzati in qualche modo, ma queste query dovrebbero darti i risultati desiderati. Condividono gli stessi primi 3 CTE che generano il diff_max valore per ogni data_max . Nella prima query cerchiamo solo una modifica in quel valore (da NULL a un valore o una diminuzione del valore) per generare le righe di output. Il 4° e il 5° CTE della seconda query sono simili alla prima query, ma aggiungiamo un RANK al diff_max valori, quindi possiamo JOIN il valore minimo (con relativa data associata) al date_diff_from e date_diff_to valori dal 6° CTE (che è la stessa della mia risposta al tuo altra domanda ).

Domanda 1:

WITH cte AS (SELECT DATE(`date_time`) AS `date`,
                    `data`,
                    MAX(`data`) OVER (ORDER BY `date_time`) AS `data_max`
             FROM `test`),
cte2 AS (SELECT `date`,
                `data`,
                `data_max`,
                CASE WHEN `data` < `data_max` THEN `data` - `data_max` END AS `data_diff`
         FROM cte),
cte3 AS (SELECT `date`, 
                MIN(`data_diff`) OVER (PARTITION BY `data_max` ORDER BY `date`) AS `diff_max`
         FROM cte2),
cte4 AS (SELECT `date`, `diff_max`, LAG(`diff_max`) OVER (ORDER BY `date`) AS `old_diff_max`
         FROM cte3)
SELECT `date`, `diff_max`
FROM cte4
WHERE `diff_max` < `old_diff_max` OR `old_diff_max` IS NULL AND `diff_max` IS NOT NULL

Uscita:

date        diff_max
2017-01-04  -3
2017-01-09  -7
2017-01-11  -10
2017-01-13  -2

Domanda 2:

WITH cte AS (SELECT DATE(`date_time`) AS `date`,
                    `data`,
                    MAX(`data`) OVER (ORDER BY `date_time`) AS `data_max`
             FROM `test`),
cte2 AS (SELECT `date`,
                `data`,
                `data_max`,
                CASE WHEN `data` < `data_max` THEN `data` - `data_max` END AS `data_diff`
         FROM cte),
cte3 AS (SELECT `data_max`, `date`, 
                MIN(`data_diff`) OVER (PARTITION BY `data_max` ORDER BY date) AS `diff_max`
         FROM cte2),
cte4 AS (SELECT `data_max`, `date`, `diff_max`, 
                LAG(`diff_max`) OVER (ORDER BY `date`) AS `old_diff_max`
         FROM cte3),
cte5 AS (SELECT `date`, `diff_max`, 
                RANK() OVER (PARTITION BY `data_max` ORDER BY `diff_max`) AS `diff_rank`
         FROM cte4
         WHERE `diff_max` < `old_diff_max` OR `old_diff_max` IS NULL AND `diff_max` IS NOT NULL),
cte6 AS (SELECT `data_max`, 
                MIN(CASE WHEN `data_diff` IS NOT NULL THEN date END) AS diff_date_from,
                MAX(CASE WHEN `data_diff` IS NOT NULL THEN date END) AS diff_date_to
         FROM cte2
         GROUP BY `data_max`
         HAVING diff_date_from IS NOT NULL)
SELECT diff_date_from, diff_date_to, `date` AS diff_max_date, `diff_max`
FROM cte6
JOIN cte5 ON cte5.date BETWEEN cte6.diff_date_from AND cte6.diff_date_to
WHERE cte5.diff_rank = 1

Uscita:

diff_date_from  diff_date_to    diff_max_date   diff_max
2017-01-04      2017-01-06      2017-01-04      -3
2017-01-09      2017-01-11      2017-01-11      -10
2017-01-13      2017-01-13      2017-01-13      -2

Demo su dbfiddle