Question

我有两张桌子。

表1包含订单和客户代码。表2包含带有发行代码的订单。

我需要能够从表1中返回客户的不同订单数量以及客户对发行代码为“F＆＃39; F＆＃39;从表2开始。然后最终的字段将是两者的比率。发行数量/订单数量。我正在使用AS400 / DB2 SQL。任何帮助将不胜感激。

Customer ORcnt IScnt IssueRatio cust1 450 37 0.082 cust2 255 12 0.047 cust3 1024 236 0.230 cust4 450 37 0.082

Answer 1

您可以在问题表中使用outer join，在count使用distinct。这样的事情取决于你的表定义：

select o.customercode, 
       count(distinct o.orderid), 
       count(distinct i.orderid), 
       count(distinct i.orderid)/count(distinct o.orderid) ratio
from table1 o
      left join table2 i on o.orderid = i.orderid and i.issuecode = 'F'
group by o.customercode

有些数据库需要将比率转换为小数 - 我不确定db2。如果需要，一种方法是将结果乘以1.0：

1.0*count(distinct i.orderid)/count(distinct o.orderid)

此外，distinct可能不需要count - 取决于您的数据......

Answer 2

如果我理解正确，这是一个join查询以及条件聚合：

select t1.customer, count(*) as ordercnt,
       sum(case when issuecode = 'F' then 1 else 0 end) as issuecnt,
       avg(case when issuecode = 'F' then 1.0 else 0 end) as issuep
from table1 t1 join
     table2 t2
     on t1.orderid = t2.orderid
group by t1.customer;

Answer 3

我这样做了几个子查询，使其在您提出的问题描述方面更具可读性。 sgeddes＆＃39;解决方案可能也有效（并且可能表现更好），具体取决于数据的精确结构。

SELECT t.customer,
       count(t.orderID_All),
       count(t.orderID_F),
       count(t.orderID_F)/count(t.orderID_All)
FROM
  (SELECT orders.customer,
          orders.orderID AS orderID_All,
          issues.orderID AS orderID_F /*assuming primary/unique key is customer-orderID*/
   FROM table1 orders
   LEFT OUTER JOIN /*you want *all* orders on the left and just orders w/ 'F' on the right*/
     (SELECT DISTINCT orderID
      FROM table2
      WHERE issuecode = 'F') issues ON orders.orderID = issues.orderID) t
GROUP BY t.customer;

SQL两个表与连接计数不同

3 个答案: