Question

我有一个“活动”表，一个“客户”表和一个“customer_activity”表。在“活动”表中，每个活动都有自己的ID和开始，结束年份：因此，每行代表一个活动，第一列是开始年份，第二列是结束年份（比如说，以下是名称为X1的特定客户的活动）。

    Start   End    Act_ID
    2007    2008    1
    2007    2008    2
    2009    2009    3
    2008    2008    4
    2008    2011    5
    2007    2008    6
    2007    2008    7
    2006    2007    8
    2006    2006    9
    2011    2013    10
    2011    2013    11

表“customer”具有客户ID和客户名称。最后表“customer_activity”具有客户ID和活动ID。我希望按客户名称查询（比如姓名为X1的客户）并得到如下表格：

        Year  New   Total
        2006   2      2
        2007   4      5  
        2008   1      4
        2009   1      2
        2010   0      1
        2011   2      3
        2012   0      2
        2013   0      2

我使用mariadb 10.1.10。有人可以帮帮我吗？

Answer 1

如果您有年份列表，可以使用join和聚合：

select y.yyyy,
       sum(case when y.yyyy = ca.start then 1 else 0 end) as news,
       count(ca.customer_id) as total
from (select 2007 as yyyy union all select 2008 union all . . .
      select 2013
     ) y left join
     customer_activity ca
     on y.yyyy between ca.start and ca.end left join
     customer c
     on ca.customer_id = c.customer_id and c.name = 'X1'
group by y.yyyy
order by y.yyyy;

生成此类年份列表的最佳方式取决于数据库。

Answer 2

替换了相关的列名后，您可以尝试这样做：

select a.start, count(*) as total, count(c.id) as new
from (select distinct(start) from activity) a 
       left join activity b 
       on a.start between b.start and b.end 
       left join activity c
       on b.id=c.id and a.start=c.start
where b.id in (select customer_activity.id
            from customer left join customer_activity
            on customer.id = customer_activity.customer_id
            where customer.name = "X1" ) 
group by a.start

SQL

2 个答案: