MYSQL、1、数据统计按天、月、年，2、区间时间内按月统计，无数据返回0

目录

1、数据统计按天、月、年

2、区间时间内按月统计

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1、数据统计按天、月、年

1、DATE_ADD() 函数向日期添加指定的时间间隔。

语法：
DATE_ADD(date,INTERVAL expr unit)

date 参数是合法的日期表达式。expr 参数是您希望添加的时间间隔。unit是指定的时间间隔类型单位。

unit参数可以是下列值：
unit值

MICROSECOND
SECOND
MINUTE
HOUR
DAY
WEEK
MONTH
QUARTER
YEAR
SECOND_MICROSECOND
MINUTE_MICROSECOND
MINUTE_SECOND
HOUR_MICROSECOND
HOUR_SECOND
HOUR_MINUTE
DAY_MICROSECOND
DAY_SECOND
DAY_MINUTE
DAY_HOUR
YEAR_MONTH

举例如下：

2、DATE_SUB() 函数从日期减去指定的时间间隔。
语法：
DATE_SUB(date,INTERVAL expr unit)
date 参数是合法的日期表达式。expr 参数是您希望添加的时间间隔。unit是指定的时间间隔类型单位。

所用的unit单位和上面的DATE_ADD()完全一致

3、DAYOFYEAR(date)
date 参数是合法的日期表达式
返回date在一年中的日数, 在1到366范围内。

三、先看看执行结果，然后在详解sql

 SELECT
        left(temp.date,7) as dateAbscissa,
        IFNULL(u.unmber,0) as thisYearCost
  from(
        SELECT date_add(DATE_SUB(CURDATE(),INTERVAL dayofyear(now())-1 DAY), interval numlist.id month) AS 'date' FROM
        (
        SELECT * from
        (SELECT i AS id FROM num ) a
        where a.id <=11
        ) AS numlist
        WHERE adddate(DATE_SUB(CURDATE(),INTERVAL dayofyear(now())-1 DAY), interval numlist.id month)<=
        concat(YEAR(now()),'-12-31')) temp
        LEFT JOIN
        (
        SELECT
        left(c.statistics_date,7) AS udate,
        SUM(c.operation_number) as unmber
        FROM
        t_hospitalization_operation c
        WHERE
        1 = 1
        
        GROUP BY left(c.statistics_date,7)
        ) u on left(temp.date,7) = u.udate ORDER BY temp.date

结果如下

四、分步解释sql

前提：需要一张中间表num，数据如下


然后LEFT JOIN 本身的数据表，既可达到效果,

# 按照天数统计
 SELECT
        temp.date as dateAbscissa,
        IFNULL(u.singleDiseasesNum,0) as singleDiseasesNum,
        IFNULL(u.multidisciplinaryNum,0) as multidisciplinaryNum
  from(   SELECT DATE_ADD((date_add(date_add(last_day(now()),interval 1 day),interval -1 month)),INTERVAL  numlist.id  DAY)AS 'date' FROM
        (
        SELECT * from
        (SELECT i AS id FROM num ) a
        where a.id <=30 
        ) AS numlist
      
) temp
        LEFT JOIN
        (
        SELECT
        DATE(c.create_time) AS udate,
        COUNT(if( c.audit_opinion='3' ,1,NULL) )as singleDiseasesNum,  
				COUNT(if( c.audit_opinion='4' ,1,NULL) )as multidisciplinaryNum 
        FROM
        t_mdt_apply_list c
        WHERE
        1 = 1
        
        GROUP BY DATE(c.create_time)
        ) u on DATE(temp.date) = u.udate ORDER BY temp.date

2、区间时间内按月统计

SELECT
    LEFT (temp.yearAndMonth, 7) AS dataV,
    IFNULL(u.valueK1, 0) AS valueK
FROM
    (
select date_format(`date`, '%Y-%m') yearAndMonth
from (select adddate('1970-01-01', interval
            t2.i * 100 + t1.i * 10 + t0.i month) `date`
      from (select 0 i union select 1 union
      select 2 union select 3 union
      select 4 union select 5 union
      select 6 union select 7 union
      select 8 union select 9) t0,
     (select 0 i union select 1 union
      select 2 union select 3 union
      select 4 union select 5 union
      select 6 union select 7 union
      select 8 union select 9) t1,
     (select 0 i union select 1 union
      select 2 union select 3 union
      select 4 union select 5 union
      select 6 union select 7 union
      select 8 union select 9) t2) a
where `date` >=DATE_FORMAT(startTime, '%Y-%m') and date <= DATE_FORMAT(endTime, '%Y-%m')
    ) temp