Mysql method to find the average value of a time period: first, splice the sql statement in the storage process; then according to the start time and end time, the while loop adds a period of time each time; finally, average the time period.

The operating environment of this tutorial: Windows 7 system, mysql version 8.0.22, Dell G3 computer.
Mysql method to find the average value of a time period:
Idea: In the stored procedure, splice sql statements. According to the start time and end time, the while loop adds a period of time each time.
DROP PROCEDURE IF EXISTS `get_avg`; DELIMITER ;; CREATE DEFINER=`root`@`%` PROCEDURE `get_avg`(in iStartTime datetime, in iEndTime datetime) BEGIN declare vSql varchar(10240) default ''; declare vNextTime datetime; while(iStartTime < iEndTime) do -- 每次加一个小时 set vNextTime = date_add(iStartTime,interval 3600 second); -- 单引号是特殊字符,要表示单引号,使用 '' 进行转义 set vSql = concat(vSql,'union select 100, avg(`value`) from t1 where time between ''',iStartTime,''' and ''', vNextTime,''' '); set iStartTime = vNextTime; end while; set vSql = substring(vSql,7); -- 看看拼接的字符串是否正确 -- select vSql; set @vSql = vSql; prepare stmt from @vSql; execute stmt; deallocate prepare stmt; END ;; DELIMITER ;
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