内联视图中的聚合函数

Question

我正在尝试为 Pervasive 数据库编写一些 SQL，但我的查询无法正常工作。

让我举一个简单的例子。假设我有以下 table:

购买：

OrderNumber     CustomerName
 55             Amy
 56             Dan
 57             Bob
 58             Dan
 59             Dan
 60             Bob
 61             Amy
 62             Cindy
 63             Dan

现在我可以使用查询 select count(OrderNumber) as "Number of orders palced", CustomerName from PURCHASES group by CustomerName order by count(OrderNumber) desc 来获取内联视图的结果：

Number of orders placed                CustomerName
          4                            Dan
          2                            Amy
          2                            Bob
          1                            Cindy

但我不想就此打住，我想知道每个 "Number of orders placed" 有多少客户，但我无法正确查询。

我想将其用作子查询，如下所示：

select x."Number of orders placed",count(x.CustomerName) as
       "Number of customers that have purchased this many orders" from 
(
    select count(OrderNumber) as "Number of orders placed", CustomerName from PURCHASES 
    group by CustomerName 
) x
group by x."Number of orders placed"

我认为我的查询失败得很惨，因为列标签不是引用子查询的正确方法。我想要得到的结果应该是这样的：

Number of orders placed           Number of customers...
      4                            1
      2                            2
      1                            1

感谢帮助和解释

Answer 1

除了内联视图中的 order by 外，我没有发现您的查询有任何问题。

select x."Number of orders placed",count(x.CustomerName) as
       "Number of customers that have purchased this many orders" 
from 
(select count(OrderNumber) as "Number of orders placed", CustomerName 
 from PURCHASES 
 group by CustomerName
) x
group by x."Number of orders placed"

内联视图中的聚合函数

Aggregate function in inline view

sql

pervasive