How to sample data for the last 24 hours in hourly mode?

Question

MySQL

For example, you need to display all the data for the last day but ... from 00 to 6 hours, from 6 to 12 hours, from 12 to 18, from 10 to 24. How to build such a query? Or one request and then how to process it in php? (again - how to do it?)

Answer 1

SELECT
   FLOOR(HOUR(date_time) / 6) AS period, 
   AVG(temperature) AS avg_temperature 
FROM table_name 
WHERE date_time > DATE_SUB(NOW(), INTERVAL 1 DAY)
GROUP BY FLOOR(HOUR(date_time) / 6)

Answer 2

group by case when hour(<field>) between ...