Question

所以我有一个这样的表：

Taxi  Client  Time
Tom   A       1
Tom   A       2
Tom   B       3
Tom   A       4 
Tom   A       5
Tom   A       6
Tom   B       7
Tom   B       8     
Bob   A       1
Bob   A       2
Bob   A       3

，预期结果将是这样：

Tom    3
Bob    1

我已经使用分区函数对连续值进行计数，但是结果变为：

Tom    A     2
Tom    A     3
Tom    B     2
Bob    A     2

请帮助，我的英语不好，谢谢！

Answer 1

使用非重复计数

  select taxi ,count( distinct cient)
  from table_name
  group by taxi

您的预期输出似乎不正确

Answer 2

我看不到您从哪里获得3。如果您要尝试按照自己的问题回答问题，并且仅按连续的顺序按客户分组，然后获取不同的分组数量，那么我可以通过以下查询为您提供帮助。鲍勃（Bob）有1组，汤姆（Tom）有4组。

按出租车划分，按出租车排序，时间，并检查此客户是否与该出租车的先前客户匹配。如果是，则不计此行。如果否，请计数此行，这是一个新组。

SELECT FEE.taxi,
       SUM(FEE.clientNotSameAsPreviousInSequence)
FROM
(
    SELECT taxi,
           CASE
               WHEN PreviousClient IS NULL THEN
                   1
               WHEN PreviousClient <> client THEN
                   1
               ELSE
                   0
           END AS clientNotSameAsPreviousInSequence
    FROM
    (
        SELECT *,
               LAG(client) OVER (PARTITION BY taxi ORDER BY taxi, time) AS PreviousClient
        FROM table
    ) taxisWithPreviousClient
) FEE
GROUP BY FEE.taxi;

Answer 3

这是空白和岛屿问题的变体。您可以使用窗口函数来解决它：

select taxi, count(*)
from (select t.taxi, t.client, count(*) as num_times
      from (select t.*,
                   row_number() over (partition by taxi order by time) as seqnum,
                   row_number() over (partition by taxi, client order by time) as seqnum_c
            from t
           ) t
      group by t.taxi, t.client, (seqnum - seqnum_c)
      having count(*) >= 2
    )
group by taxi;

SQL查找行中连续的数字并将其分组

3 个答案: