Question

我有两列来自我的SQL查询 - 月，值，即值按月来临。我的要求是在3个月的时间内将这些月份分成几个月......并且值应该是这3个月的平均值。例如，我有以下数据 -

Month   Values
Mar-14  50
Apr-14  51
May-14  52
Jun-14  53
Jul-14  54
Aug-14  55
Sep-14  56
Oct-14  57
Nov-14  58
Dec-14  59
Jan-15  60
Feb-15  61
Mar-15  62
Apr-15  63
May-15  64
Jun-15  65
Jul-15  66
Aug-15  67
Sep-15  68
Oct-15  69
Nov-15  70
Dec-15  71
Jan-16  72
Feb-16  73
Mar-16  74
Apr-16  75
May-16  76
Jun-16  77
Jul-16  78
Aug-16  79
Sep-16  80
Oct-16  81
Nov-16  82
Dec-16  83
Jan-17  84
Feb-17  85
Mar-17  86

如何在MySql-

中实现以下输出

3 Months Clubing    Avg of Values
Mar-14  51
Jun-14  54
Sep-14  57
Dec-14  60
Mar-15  63
Jun-15  66
Sep-15  69
Dec-15  72
Mar-16  75
Jun-16  78
Sep-16  81

先谢谢

Answer 1

有点乱，但你可以使用变量 - 假设你有一个递增的id列（或者你可以订购的东西）

drop table if exists t;
create table t(id int auto_increment primary key,Month varchar(10), Valus int);
insert into t (month,valus) values 
('Mar-14', 50), 
('Apr-14', 51),
('May-14', 52), 
('Jun-14', 53), 
('Jul-14', 54), 
('Aug-14', 55), 
('Sep-14', 56), 
('Oct-14', 57), 
('Nov-14', 58), 
('Dec-14', 59); 

select  id,mth,rt 
from
(
select  id,month,valus,
          @count:=@count+1 counter,
          if(@count=1,@mth:=month,@mth:=@mth) mth,
          if(@count=1,@block:=@block+1,@block:=@block) block,
          if(@count<3,@sum:=@sum+valus,@sum:=(@sum+valus) / 3) rt,
          if(@count=3,@count:=0,@count:=@count) creset,
          if(@count=0,@sum:=0,@sum:=@sum) sumreset

from t
cross join (select @m ='',@count:=0,@sum:=0,@block:=0,@mth:='') s
order by id
)t
where counter = 3;
+----+--------+------+
| id | mth    | rt   |
+----+--------+------+
|  3 | Mar-14 |   51 |
|  6 | Jun-14 |   54 |
|  9 | Sep-14 |   57 |
+----+--------+------+
3 rows in set (0.03 sec)

稍微不那么凌乱但是使用sql的avg函数并使用变量填充3个月块中的第一个月

select  block,mth,avg(valus)
from
(
select  id,month,valus,
          @count:=@count+1 counter,
          if(@count=1,@mth:=month,@mth:=@mth) mth,
          if(@count=1,@block:=@block+1,@block:=@block) block,
          if(@count=3,@count:=0,@count:=@count) creset
from t
cross join (select @block:=0,@count:=0,@mth:='') s
order by id
) t
group by block,mth
order by block,mth

+-------+--------+------------+
| block | mth    | avg(valus) |
+-------+--------+------------+
|     1 | Mar-14 |    51.0000 |
|     2 | Jun-14 |    54.0000 |
|     3 | Sep-14 |    57.0000 |
|     4 | Dec-14 |    59.0000 |
+-------+--------+------------+
4 rows in set (0.05 sec)

Answer 2

试试这个

 create temporary table tab (month1 varchar(30), id int);

insert into tab (month1,id)
values('Mar-14'  ,50),
('Apr-14' ,51),
('May-14'  ,52),
('Jun-14'  ,53),
('Jul-14'  ,54),
('Aug-14'  ,55),
('Sep-14'  ,56),
('Oct-14'  ,57),
('Nov-14'  ,58),
('Dec-14'  ,59),
('Jan-15'  ,60),
('Feb-15'  ,61),
('Mar-14'  ,62);

set @row_number = 0;
select *
from tab where (@row_number := @row_number+1)%3= 1;

<强>结果

 month1   id
'Mar-14' '50'
'Jun-14' '53'
'Sep-14' '56'
'Dec-14' '59'
'Mar-14' '62'

如何在MySql中添加值

2 个答案: