如果mysql中不存在数据，如何添加总计为0的月份名称？

我需要获取用户从创建日期到当前日期的数据，按月份名称和年份以及每个月的总价

尝试1：

输出：

month           year    total
July            2019    360
September       2019    2160
October         2019    360

预期产出：

All month name and total will be 0 if data not exist. 

month           year    total
Jan             2018    0
Feb             2018    0
...
Dec             2018    0
Jan             2019    0
Feb             2019    0
Mar             2019    0
Apr             2019    0
May             2019    0
Jun             2019    0
July            2019    360
Aug             2019    0
Sep             2019    2160
Oct             2019    360
Nov             2019    0
Dec             2019    0

经过一些RND，我找到了一种方法，我也尝试过，但现在起作用了

尝试2：

这是我的链接

有人能帮我解决这个问题吗

---

提前谢谢

如果表中有所有月份的数据，但没有该id的数据，则可以切换到条件聚合：

SELECT MONTHNAME(start_time) as month, YEAR(start_time) as year, 
       SUM(CASE WHEN t1.id = 33 THEN price ELSE 0 END) as total
FROM table t1
GROUP BY YEAR(start_time),MONTHNAME(start_time)
ORDER BY MIN(start_time);

继续使用LEFT JOIN，但只使用一次整数生成器（最多12个），而不是月份名称，在ORDER BY子句中也很容易使用，因为您可以通过monthname函数获取月份名称。根据你的第二个问题，我考虑了今年。因此，请使用：

SET @year=YEAR(NOW());

SELECT 
      MONTHNAME(STR_TO_DATE(concat(YEAR(NOW()),',',m.month,',1'),"%Y,%m,%d")) as month,
      @year as year , SUM( COALESCE( pu.price, 0) ) as total
  FROM (
        SELECT rn as month 
          FROM
          (
           SELECT @rn := if(@i = @rn, @rn + 1, 1) as rn,
                  @i := @i+1
             FROM information_schema.character_sets
             JOIN (SELECT @i := 0, @rn := 0) as q_iter
            LIMIT 12
          ) q
        ) AS m
   LEFT JOIN table_u pu ON MONTH(pu.start_time) = m.month
    AND YEAR(pu.start_time) = @year
    AND ID = 33
  GROUP BY m.month
  ORDER by m.month;

2018年初至本年末编辑：

---

使用用户变量创建不存在的年-月对：

SELECT monthname(str_to_date(concat_ws(',',ym.month,'01,01'),'%m,%d,%y')) month
     , ym.year year 
     , sum(price)
  FROM table1 t1
    RIGHT JOIN( SELECT @year  := if(@month=12, @year+1, @year   ) year
                    , @month := if(@month=12, 1      , @month+1) month
                 FROM table1
                    , ( SELECT @startYear := min(start_time)
                             , @endYear   := year(now())
                             , @month := 12
                             , @year  := min(start_time)-1
                          FROM table1
                      ) t
                 WHERE (@year,@month) < (@endYear,12)
             ) ym
      ON    ym.year  = year(t1.start_time)
        AND ym.month = month(t1.start_time)
  GROUP BY year(t1.start_time)
         , month(t1.start_time)

ym派生表将提供从表1中最小年份开始到当前年份的年-月对。 最内层的选择用于变量初始化。

您可以尝试以下操作：

SELECT to_char(start_time,'month')MONTH,to_char(start_time,'yyyy')YEAR,SUM(price)total 
FROM   TABLE_NAME
GROUP BY to_char(start_time,'month'),to_char(start_time,'yyyy')

---

最后，我得到了我想要的正确输出

select
DATE_FORMAT(m1, '%M - %Y')

from
(
  select
  ('2013-07-23')
  +INTERVAL m MONTH as m1
  from
  (
     select @rownum:=@rownum+1 as m from
     (select 1 union select 2 union select 3 union select 4) t1,
     (select 1 union select 2 union select 3 union select 4) t2,
     (select 1 union select 2 union select 3 union select 4) t3,
     (select 1 union select 2 union select 3 union select 4) t4,
     (select @rownum:=-1) t0
  ) d1
) d2
  where m1<=NOW()
  order by m1

---

谢谢你的回答。在我的情况下，我不可能在一年中为特定用户指定月份名称。例如，他有3个月没有工作了，然后我需要给他显示相应月份的0。@Sachinsah。您没有抓住要点，显然没有运行查询。如果任何id的数据中都有月份，则使用此查询的结果集中会有月份。数据仅为33。好的，我稍后会尝试并让您知道。我已经检查过了，今年的效果很好。我只需要再升一级。例如，我有一个日期2018-10-10，然后我需要从2010年的月份到当前月份的数据。我从未想过我可以运行这种类型的查询。也许这需要一些时间来理解它是如何工作的好的，我修复了Sachinsah。谢谢BarbarosÖzhan。我会查一查让你知道的。谢谢你的回复。这对我不起作用。我得到了这个输出。月年合计价格一月零360一月零2160一月零360你能检查我的预期输出吗谢谢你的回复。我会检查并让您知道。to_char是默认函数？是的！to_char是默认函数。“用于日期”将转换为字符串。有关更多信息，请参阅下面的链接。好的，我会再试一次并让您知道。函数TO_CHAR不存在

SELECT monthname(str_to_date(concat_ws(',',ym.month,'01,01'),'%m,%d,%y')) month
     , ym.year year 
     , sum(price)
  FROM table1 t1
    RIGHT JOIN( SELECT @year  := if(@month=12, @year+1, @year   ) year
                    , @month := if(@month=12, 1      , @month+1) month
                 FROM table1
                    , ( SELECT @startYear := min(start_time)
                             , @endYear   := year(now())
                             , @month := 12
                             , @year  := min(start_time)-1
                          FROM table1
                      ) t
                 WHERE (@year,@month) < (@endYear,12)
             ) ym
      ON    ym.year  = year(t1.start_time)
        AND ym.month = month(t1.start_time)
  GROUP BY year(t1.start_time)
         , month(t1.start_time)

SELECT to_char(start_time,'month')MONTH,to_char(start_time,'yyyy')YEAR,SUM(price)total 
FROM   TABLE_NAME
GROUP BY to_char(start_time,'month'),to_char(start_time,'yyyy')

select
DATE_FORMAT(m1, '%M - %Y')

from
(
  select
  ('2013-07-23')
  +INTERVAL m MONTH as m1
  from
  (
     select @rownum:=@rownum+1 as m from
     (select 1 union select 2 union select 3 union select 4) t1,
     (select 1 union select 2 union select 3 union select 4) t2,
     (select 1 union select 2 union select 3 union select 4) t3,
     (select 1 union select 2 union select 3 union select 4) t4,
     (select @rownum:=-1) t0
  ) d1
) d2
  where m1<=NOW()
  order by m1