mysql 统计时补全不存在的日期

需求

将指定时间内的数据进行统计，并将无数据的日期补充 0

task_logs 为目标表

实际数据

SELECT DATE_FORMAT(create_time,'%Y-%m-%d') create_time FROM task_logs GROUP BY DATE_FORMAT(create_time,'%Y-%m-%d');

补全到目标时间后

SELECT
		@cdate := date_add( @cdate, INTERVAL - 1 DAY ) AS date_str 
	FROM
		( SELECT @cdate := date_add( DATE_FORMAT(create_time,'%Y-%m-%d'), INTERVAL + 1 DAY ) FROM task_logs ) tmp1 
	WHERE
		@cdate > '2023-02-01';

最终统计

将统计数据与生成的时间数据进行关联查询

SELECT
	date_str,
	create_time,
	IFNULL( tl.c, 0 ) count 
FROM
	(
	SELECT
		DATE_FORMAT( create_time, '%Y-%m-%d' ) create_time,
		count( 1 ) c 
	FROM
		task_logs 
	GROUP BY
	DATE_FORMAT( create_time, '%Y-%m-%d' )) tl
	RIGHT JOIN (
	SELECT
		@cdate := date_add( @cdate, INTERVAL - 1 DAY ) AS date_str 
	FROM
		( SELECT @cdate := date_add( DATE_FORMAT( create_time, '%Y-%m-%d' ), INTERVAL + 1 DAY ) FROM task_logs ) tmp1 
	WHERE
		@cdate > '2023-02-10' 
	) tl_temp ON date_str = DATE_FORMAT( create_time, '%Y-%m-%d' ) 
GROUP BY
	date_str 
ORDER BY
	date_str DESC