SQL Server挑战性问题-寻找第一买家，第二/第三买家，第四或更多买家

Question

祝大家节日快乐

我被分配编写一个SQL查询，以显示在特定数据范围和位置中购买特定产品的购买者数量。
我需要找到以下内容：

1. 有史以来第一次买家。
2. 第2/3次买家。
3. 第4次或更多时间的买家。

我能够使用以下查询首次获得买家; 但找不到第二/第三买家，第四或更多买家。 有人可以帮忙。

DECLARE @from_dt        datetime
DECLARE @Day_End_dt     datetime

SET @from_dt =     '10/01/2010'
SET @Day_End_dt =  '12/29/2010'


select count(B.buyer_id) as California_1st_time_buyer
from
--LIST OF ALL BUYERS AND FIRST PURCHASED DATE THRU END OF DATE RANGE (10/1/98 - 12/28/10)
(select distinct buyer_id, min(purchased_date_time) as First_timer
from product_details
where purchased_date <@Day_End_dt
group by buyer_id
)A,
--LIST OF CALIFORNIA BUYERS AND FIRST PURCHASED DATE IN DATE RANGE (12/1/10 - 12/28/10)
(select distinct buyer_id, min(purchased_date_time) as First_timer_ca_in_date_range
from product_details
where purchased_date >=@from_d
and purchased_date <@Day_End_dt
and location = 'CA'
group by buyer_id
)B
where A.buyer_id = B.buyer_id
and A.First_timer = B.First_timer_ca_in_date_range



Input sample:
purchased_date_time     purchased_date      buyer_id
12/7/2010 12:30:00 PM       12/7/2010       5627242
--------------------------------------------------------------------
12/9/2010 4:30:00 PM         12/9/2010       9231374
12/19/2010 11:30:00 AM     12/19/2010      9231374
--------------------------------------------------------------------
12/9/2010 12:10:00 AM       12/9/2010       8061088
12/15/2010 5:00:00 PM       12/15/2010      8061088
12/21/2010 6:00:00 PM       12/21/2010      8061088
--------------------------------------------------------------------
12/1/2010 12:30:00 PM       12/1/2010       2288101
12/12/2010 6:30:00 PM       12/12/2010      2288101
12/27/2010 7:30:00 PM       12/27/2010      2288101
12/28/2010 6:30:00 PM       12/28/2010      2288101
--------------------------------------------------------------------
12/9/2010 10:45:00 AM       12/9/2010       2510454
12/16/2010 9:45:00 PM       12/16/2010      2510454
12/19/2010 4:19:00 AM       12/19/2010      2510454
12/22/2010 7:05:00 AM       12/22/2010      2510454
12/29/2010 2:30:00 AM       12/29/2010      2510454
--------------------------------------------------------------------
Output sample:
1st buyers =5 --count buyer_id who purchased the product first time ever in date range (12/1/10 - 12/28/10)

2nd/3rd buyers =7 --count buyer_id who purchased the product 2nd/3rd time in date range (12/1/10 - 12/28/10)

4th or more buyers =3  --count buyer_id who purchased the product 4th time or more in date range (12/1/10 - 12/28/10)

请注意，这些买家仅来自上述日期范围。 假设如果某位买家在2010年12月1日之前进行了三次购买，然后又在2010年1月1日再次购买，那么他将被视为第四定时器购买者。

Answer 1

我不完全了解您想做什么。 如果您可以使用表结构，几个示例行和预期的输出来更新问题，它将有所帮助。

无论如何，这是一个尝试:)

以下查询应为您提供进行了四次或更少购买的购买者列表。 还不清楚您是否只想计算购买次数，或者是否也需要实际购买日期，所以我也添加了日期（对于前4次购买）。 如果买方仅进行了1次购买，则该行将在购买2/3/4列中显示NULL。

如果要包括日期范围或按位置过滤，则这些条件将放在内部选择中。

select buyer_id
      ,count(*) as purchases
      ,max(case when purchase_no = 1 then purchased_date end) as purchase_1
      ,max(case when purchase_no = 2 then purchased_date end) as purchase_2
      ,max(case when purchase_no = 3 then purchased_date end) as purchase_3
      ,max(case when purchase_no = 4 then purchased_date end) as purchase_4
  from (select buyer_id
              ,purchased_date
              ,row_number() over(partition by buyer_id
                                     order by purchased_date) as purchase_no
          from product_details
       )
 where purchase_no <= 4
group by buyer_id;

让我知道它是否有效。

Answer 2

此查询将提供日期范围内的Buyer_id和购买次数：

DECLARE @from_dt datetime
DECLARE @Day_End_dt datetime
SET @from_dt =     '10/01/2010'
SET @Day_End_dt =  '12/29/2010' 

SELECT [buyer_id],COUNT([buyer_id]) AS purchases_in_period
  FROM [product_details]
  WHERE purchased_date_time between @from_dt and @Day_end_dt
  -- OPTIONAL LOCATION FILTER
  -- AND [location] = 'CA'
  GROUP BY [buyer_id]
GO

如果你使用这个作为一个嵌套查询可以算buyer_id与给定的数值purchases_in_period 。

Answer 3

我通常将其作为单独查询的组合来处理。

      select buyer from T,  1 as FirstTimeBuyer, 0 as SecondTimeBuyer, 0 as thirdtimebuyer
      where date is in the specified range
      group by buyer having count(t.id) = 1
      UNION
       select buyer from T,  0 as FirstTimeBuyer, 1 as SecondTimeBuyer, 0 as thirdtimebuyer
      where date is in the specified range
      group by buyer having count(t.id) = 2
      UNION
       select buyer from T,  0 as FirstTimeBuyer, 0 as SecondTimeBuyer, 1 as thirdtimebuyer
      where date is in the specified range
      group by buyer having count(t.id) = 3