mysql统计最近6天或6周或6个月的数据，没有数据自动补0
mysql查询最近6天的数据，没有数据自动补0; 以时间为基准，如果那天没数据自动补0；
首先利用系统表创建一个虚拟的数据表:
参考:https://blog.csdn.net/sq_com/article/details/84997563
SELECT (@s:=@s+1) AS _index,STR_TO_DATE(DATE(DATE_SUB(CURRENT_DATE,INTERVAL @s DAY)),'%Y-%c-%d') AS _date
FROM information_schema.CHARACTER_SETS,(SELECT @s:=-1) AS init WHERE @s < 5 ORDER BY _date这样就有可以得到一张临时的数据表；information_schema.CHARACTER_SETS为系统表（设置为随便一张系统表都可以）。
(今天日期为2019-07-16)
然后在LEFT JOIN 你要实际查出来的数据，例如以下是我查出的数据:
SELECT
SUM(IFNULL(o.fare,0)) AS allFare,
STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%c-%d'),'%Y-%c-%d') AS finish_date
FROM orders o
WHERE o.employee_id = 17 AND o.order_status = 2
AND STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%c-%d'),'%Y-%c-%d') >='2019-07-11 00:00:00'
AND STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%c-%d'),'%Y-%c-%d') <= '2019-07-16 00:00:00'
GROUP BY finish_date
ORDER BY finish_date 结果：
上面两者合并起来:
SELECT tbl._date AS dateString,IFNULL(tbr.allFare,0) as balance
FROM (SELECT (@s:=@s+1) AS _index,STR_TO_DATE(DATE(DATE_SUB(CURRENT_DATE,INTERVAL @s DAY)),'%Y-%c-%d') AS _date
FROM information_schema.CHARACTER_SETS,(SELECT @s:=-1) AS init WHERE @s<5 ORDER BY _date) AS tbl
LEFT JOIN(SELECT
SUM(IFNULL(o.fare,0)) AS allFare,
STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%c-%d'),'%Y-%c-%d') AS finish_date
FROM orders o
WHERE o.employee_id = 17 AND o.order_status = 2
AND STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%c-%d'),'%Y-%c-%d') >='2019-07-11 00:00:00'
AND STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%c-%d'),'%Y-%c-%d') <= '2019-07-16 00:00:00'
GROUP BY finish_date
ORDER BY finish_date
) AS tbr ON tbl._date = tbr.finish_date GROUP BY tbl._date;得到的结果如下:
用到的Myql函数有:
DATE_SUB() 函数：从日期减去指定的时间间隔;
DATE() 函数：返回日期或日期/时间表达式的日期部分。
STR_TO_DATE()函数：按照指定日期或时间显示格式 将字符串转换为日期或日期时间类型；
DATE_FORMAT()函数：按照指定日期或时间显示格式 输出日期或日期时间；
IFNULL() 函数：用于判断第一个表达式是否为 NULL，如果为 NULL 则返回第二个参数的值，如果不为 NULL 则返回第一个参数的值。
统计6周的也和上面一样:
SELECT tbl._date AS dateString,IFNULL(tbr.allFare,0) as balance
FROM ( SELECT (@s:=@s+1) AS _index,WEEK(DATE(DATE_SUB(CURRENT_DATE,INTERVAL @s WEEK))) AS _date
FROM information_schema.CHARACTER_SETS,(SELECT @s:=-1) AS init WHERE @s<5 ORDER BY _date)
AS tbl
LEFT JOIN(SELECT sum(IFNULL(o.fare,0)) allfare,WEEK(o.finish_time) AS finish_date
FROM orders o
WHERE o.employee_id = 17 AND o.order_status = 2
AND WEEK(o.finish_time) >= WEEK(DATE(DATE_SUB(CURRENT_DATE,INTERVAL 5 WEEK)))
AND WEEK(o.finish_time) <= WEEK(CURRENT_DATE)
GROUP BY finish_date ORDER BY finish_date
) AS tbr ON tbl._date = tbr.finish_date GROUP BY tbl._date;结果:
其中dateString为第几周;
统计最近6个月的也一样如下:
SELECT tbl._date AS dateString,IFNULL(tbr.allFare,0) as balance
FROM ( SELECT (@s:=@s+1) AS _index,DATE_FORMAT(DATE_SUB(CURRENT_DATE,INTERVAL @s MONTH),'%Y-%m') AS _date
FROM information_schema.CHARACTER_SETS,(SELECT @s:=-1) AS init WHERE @s<5 ORDER BY _date) AS tbl
LEFT JOIN(SELECT sum(IFNULL(o.fare,0)) allfare,
DATE_FORMAT(o.finish_time,'%Y-%m') AS finish_date
FROM orders o
WHERE o.employee_id = 1 AND o.order_status = 2
AND STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%m'),'%Y-%m') >= STR_TO_DATE(DATE_FORMAT(DATE_SUB(CURRENT_DATE,INTERVAL 5 MONTH),'%Y-%m'),'%Y-%m')
AND STR_TO_DATE(DATE_FORMAT(o.finish_time,'%Y-%m'),'%Y-%m') <= STR_TO_DATE(DATE_FORMAT(CURRENT_DATE,'%Y-%m'),'%Y-%m')
GROUP BY finish_date ORDER BY finish_date
) AS tbr ON tbl._date = tbr.finish_date GROUP BY tbl._date;结果:
暂时记录下！！！