Question

这是我的示例表数据：

CustomerType     Date          Records
    1          2018-01-01        233
    2          2018-01-01         12
    1          2018-01-02          0
    2          2018-01-02         34
    1          2018-01-03          0
    2          2018-01-03         35
    1          2018-01-04          0
    2          2018-01-04          0
    1          2018-01-05       5562
    2          2018-01-05          3

我希望输出显示CustomerType为每个CustomerType提取的最大0记录条纹。换句话说，我希望每个特定CustomerType连续的最大零记录数

示例输出

CustomerType  MaxZeroRecordsStreak
      1              3
      2              1

到目前为止我得到的最远的是这样的：

SELECT CustomerType,
 (SELECT COUNT(*)
 FROM Table1 as t1
 AND Records = '0'
 AND t1.Date <= t2.Date) AS MaxZeroRecordsStreak
FROM Table2 As t2
ORDER BY CustomerType ASC;

但这显然不是我想要的。

对此复杂查询的任何帮助都将不胜感激。

Answer 1

大多数数据库都支持ANSI标准窗口函数。您可以使用row_numbers()的差异来执行此操作。以下内容获取客户类型的所有零序列：

select customertype, count(*) as num_zeros
from (select t.*,
             row_number() over (partition by records, customertype order by date) as seqnum_rt,
             row_number() over (partition by customertype order by date) as seqnum_t
      from t
     ) t
where records = 0
group by records, customertype, seqnum_t - seqnum_rt;

只需将此作为子查询使用即可获得最大值：

select customertype, max(num_zeros)
from (select customertype, count(*) as num_zeros
      from (select t.*,
                   row_number() over (partition by records, customertype order by date) as seqnum_rt,
                   row_number() over (partition by customertype order by date) as seqnum_t
            from t
           ) t
      where records = 0
      group by records, customertype, seqnum_t - seqnum_rt
     ) t
group by customertype;

SQL Query查找具有唯一记录类型的条带

1 个答案: