MYSQL根据时间统计，没有的时间补上并补0

项目中有些曲线图，需要统计月份每天的，或者年份每个月的条件数量

列如：

如下图mysql的表safety_camera_event有八条数据

1. 直接分组是得不到全部日期的，只能分组到有的日期数据

SELECT DATE_FORMAT(sce.event_date,'%Y-%m-%d') as date ,count(1) from safety_camera_event sce GROUP BY DATE_FORMAT(sce.event_date,'%Y-%m-%d')

结果:

2.我们想得到连续日期，并补0的数据需要这样来写

日的数据

SELECT t1.date_str, COALESCE(t2.date_total_count, 0) as date_total_count
    FROM(
    SELECT @cdate:= date_add(@cdate, interval - 1 day) as date_str FROM(SELECT @cdate:= date_add('2022-10-15', interval + 1 day) from security_role_resource) tmp1 WHERE @cdate > '2022-10-01'
    ) t1
    LEFT JOIN(
    SELECT DATE_FORMAT(sce.event_date, '%Y-%m-%d') as date_str, count(1) as date_total_count FROM safety_camera_event as sce WHERE sce.valid =1     AND
    YEAR(sce.event_date) = YEAR(now())
    AND
    MONTH(sce.event_date) = MONTH(now()) GROUP BY DATE_FORMAT(sce.event_date, '%Y-%m-%d')
    ) t2
    on t1.date_str = t2.date_str
    ORDER BY t1.date_str ASC

结果：

同理月的数据：

SELECT t1.date_str, COALESCE(t2.date_total_count, 0) as date_total_count
    FROM(
    SELECT DATE_FORMAT(@cdate:= (date_add(@cdate, interval - 1 month)),'%Y-%m') as date_str FROM(SELECT @cdate:= date_add('2022-10-01', interval + 1 month) from security_role_resource) tmp1 WHERE @cdate > '2022-01-01'
    ) t1
    LEFT JOIN(
    SELECT DATE_FORMAT(sce.event_date, '%Y-%m') as date_str, count(1) as date_total_count FROM safety_camera_event as sce WHERE sce.valid =1     AND
    YEAR(sce.event_date) = YEAR(now())
    GROUP BY DATE_FORMAT(sce.event_date, '%Y-%m')
    ) t2
    on t1.date_str = t2.date_str
    ORDER BY t1.date_str ASC

结果：