Question

我有一张看起来像这样的表：

_Datetime           | Value
2015-05-01 06:00:00 | 12.3
2015-05-01 06:20:00 | 12.5
2015-05-01 06:40:00 | 12.3
2015-05-01 07:00:00 | 13.5
2015-05-01 07:20:00 | 14.5
2015-05-01 07:40:00 | 14.3
2015-05-01 08:00:00 | 18.2
2015-05-01 08:20:00 | 15.0
2015-05-01 08:40:00 | 15.0

2015-05-02 06:00:00 | 19.2
2015-05-02 06:20:00 | 7.3
2015-05-02 06:40:00 | 11.4
2015-05-02 07:00:00 | 9.5
2015-05-02 07:20:00 | 7.6
2015-05-02 07:40:00 | 6.6
2015-05-02 08:00:00 | 10.4
2015-05-02 08:20:00 | 19.3
2015-05-02 08:40:00 | 15.4

2015-05-03 06:00:00 | 8.7
2015-05-03 06:20:00 | 8.6
2015-05-03 06:40:00 | 8.6
2015-05-03 07:00:00 | 21.5
2015-05-03 07:20:00 | 12.4
2015-05-03 07:40:00 | 7.3
2015-05-03 08:00:00 | 10.8
2015-05-03 08:20:00 | 12.5
2015-05-03 08:40:00 | 10.6

我想：

- 每天选择min，max和avg

- 选择发生最小值和最大值的时间（我只想选择一行 - 首先发生的行）

_Date      | _Min  |  _MinTime  |  _Max  |  _MaxTime  |  Avg    |
2015-05-01 | 12.3  |  06:00:00  |  18.2  |  08:00:00  |  14.18  |
2015-05-02 |  6.6  |  07:40:00  |  19.3  |  08:20:00  |  11.86  |
2015-05-03 |  7.3  |  07:40:00  |  21.5  |  07:00:00  |  11.22  |

我可以很容易地获得最小值，最大值和平均值，但是时间紧迫。

Answer 1

试试这个 - 每天只返回一组值。（编辑 - 添加平均值，按评论中的建议四舍五入）。

; with cte as (
select *
    , cast (_datetime as date) as [DateFormat]
    , cast (_datetime as time) as [TimeFormat]
    , row_number() over (partition by cast (_datetime as date) order by Value, _datetime) RNmin
    , row_number() over (partition by cast (_datetime as date) order by Value desc, _datetime) RNmax
    , Avg(value) over (partition by cast (_datetime as date)) as AvgVal
from MyTable
)
select a.DateFormat, a.value as MinValue, a.TimeFormat as MinTime
     , b.value as MaxValue, b.TimeFormat as MaxTime
     , cast(a.AvgVal as decimal(5,2)) as AverageValue
from Cte a
join cte b
on a.DateFormat = B.Dateformat and a.RNmin = 1 and b.RNmax = 1

Answer 2

SELECT x.*
     , min.datetime min_time
     , max.datetime max_time
  FROM 
     ( SELECT DATE(datetime) date
            , MIN(value) min_value
            , MAX(value) max_value
            , AVG(value) 
         FROM my_table 
        GROUP 
           BY DATE(datetime)
     ) x
  JOIN my_table min
    ON DATE(min.datetime) = x.date
   AND min.value = x.min_value
  JOIN my_table max
    ON DATE(max.datetime) = x.date
   AND max.value = x.max_value;

Answer 3

-

this will get you the mins.....
create table table1  
(_date datetime,
value float);

insert into table1 values (
'2015-05-01 06:00:00',  12.3)
,('2015-05-01 06:20:00',12.5)
<('2015-05-02 06:00:00', 19.2)
,('2015-05-02 06:20:00', 7.3)

select * from
 ( select min(value) as min1 ,cast(_date as date) as date1 from table1 group by cast(_date as date) )
 as i1
inner join
(select cast(_date as date) _date1,value, cast(_date as time) _time1 from table1)  as i2

on i1.min1= i2.value and
cast(i2._date1 as date)= i1.date1

SQL查询 - 查找最小值，最大值和发生最小值和最大值的时间

3 个答案: