Question

我需要计算满足某些条件的行数，这些行包含在满足其他条件的其他行定义的间隔中。示例：＆＃39;参考＆＃39;之间的行数N.值1和4满足条件＆＃39; Other_condition＆＃39; = b是N = 1，＆＃39;参考＆＃39;之间的行数N.具有满足条件的值2和5＆＃39; Other_condition＆＃39; = b是N = 2等。

  Date          Reference    Other_condition
20171111            1              a
20171112            2              a   
20171113            3              b
20171114            4              b  
20171115            5              b

我通过Hive / Impala SQL查询访问数据库，遗憾的是我不知道从哪里开始实现这样的窗口函数。我想要的半伪代码版本将是：

SELECT COUNT (DISTINCT database.Date) AS counter, Other_condition, reference
FROM database
WHERE database.Other_condition = a AND database.Reference BETWEEN 
(window function condition 1: database.Reference = 2) AND 
(window function condition 2: database.Reference = 5)
GROUP BY counter

Answer 1

你的问题很难理解。我得到了第一个条件，即＆＃34; 1＆＃34;之间的行数。和＆＃34; 4＆＃34;。

这是一个非常容易概括的方法：

select (max(case when reference = 4 then seqnum end) -
        max(case when reference = 1 then seqnum end)
       ) as num_rows_1_4
from (select t.*,
             row_number() over (order by date) as seqnum
      from t
     ) t;

HIVE / Impala查询：计算满足特定条件的行之间的行数

1 个答案: