Question

我对SQL Group By Statement

有疑问

首先这是我的表 - ＆gt; TEMP_DATA

id    |   a_id     |      date_time         |    length  |   <br>
1074  |  3   |    2016-12-07 09:13:13.490  |  1.036013  |   <br>
1075  |  1   |    2016-12-07 09:13:13.690  |  1.699601  |   <br> 
1076  |  0   |    2016-12-07 09:13:13.867  |  2.110443  |   <br> 
1077  |  3   |    2016-12-07 09:13:14.490  |  1.027660  |   <br> 
1078  |  1   |    2016-12-07 09:13:14.690  |  1.742645  |   <br> 
1079  |  0   |    2016-12-07 09:13:14.867  |  2.121963  |   <br> 
1080  |  2   |    2016-12-07 09:13:18.390  |  4.008482  |   <br>

我尝试通过id asc选择3个不同的a_id顺序的id，a_id，date_time，length 所以我用这个

SELECT DISTINCT 
    a_id, 
    Min(id) id,         
    Min(Last_Data.lenght) lenght,
    (Select date_time from temp_data
     where temp_data.id = Min(Last_Data.id)) last_time
FROM (
    SELECT *
    FROM temp_data
    where id >= 1074 and id <= 1080
) Last_Data
GROUP BY a_id
order by id asc

结果是

id    |   a_id     |      last_time         |    length  |   <br>
1074  |  3   |    2016-12-07 09:13:13.490  |  1.013928 |   <br>
1075  |  1   |    2016-12-07 09:13:13.690  |  1.699601  |   <br>
1076  |  0   |    2016-12-07 09:13:13.867  |  2.110443  |   <br>

我的ID长度值错误。我该如何解决这个问题？

P.S。：首先我在这张表中得到3个不同的a_id。然后我使用select top 3 *语句。因为两个相同的a_id可以连续出现。例如

id  |   a_id     |      date_time         |    length  |   <br>
1074  |  1   |    2016-12-07 09:13:13.490  |  1.013928 |   <br>
1075  |  1   |    2016-12-07 09:13:13.690  |  1.699601  |   <br>

Answer 1

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over

Answer 2

;with cteData as
(    
    SELECT
        t.a_id, t.id, t.date_time, t.lenght,
        row_number() over(partition by t.a_id order by t.date_time desc) rn
    FROM temp_data t
    where id >= 1074 and id <= 1080
)
select
   d.a_id, d.id, d.date_time as last_date_time, t.length
from cteData d
where d.rn = 1

SQL Group By Statement

2 个答案: