业务需求
最近要在系统中加个统计功能，要求是按指定日期范围里按天分组统计数据量，并且要能够查看该时间段内每天的数据量。

SELECT
    @cdate: = date_add(@cdate, interval - 1 day) as date_str, 0 as date_count
FROM(SELECT @cdate: = date_add(CURDATE(), interval + 1 day) from t_table1) t1

2、业务统计查询也按上述日期查询给统计日期和数量设置别名

SELECT
    FROM_UNIXTIME(m.sdate, '%Y-%m-%d') as date_str, count( * ) as date_count
from t_table1 as m
group by FROM_UNIXTIME(m.sdate, '%Y-%m-%d')

3、把两个查询用左连接合起，没数量的日期填0

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(CURDATE(), interval + 1 day) from t_table1) tmp1 WHERE @cdate > '2018 - 12 - 01'
) t1
LEFT JOIN(
    SELECT FROM_UNIXTIME(m.sdate, '%Y-%m-%d') as date_str, count(*) as date_total_count FROM t_table1 as m WHERE m.sdate between XXXX and XXXXX GROUP BY FROM_UNIXTIME(m.sdate, '%Y-%m-%d')
) t2
on t1.date_str = t2.date_str

查询结果如下图所示：