Question

我试图在给定的月份（JAN-14）中显示最受欢迎的产品（format_id），并将它们按每个format_id的计数进行分组。

这是我的查询：

select PRODUCT, AMOUNT
from (Select Order_108681091.Order_Date, order_line_108681091.Format_id as Product,   
COUNT(*) AS AMOUNT FROM order_line_108681091 
Inner Join order_108681091
On order_108681091.order_id = order_line_108681091.order_id
Where order_108681091.Order_Date like '%JAN-14%'
group by Format_id
order by AMOUNT desc);

我该怎么做？

Answer 1

您必须指定内部联接：

inner join order_108681091 ON order_1078681091.ID = order_line_018681091.ID

或类似的东西。除非您将该日期存储为字符串而不是datetime数据类型，否则您的where子句可能无法工作。

Answer 2

你说你有条件，所以让我们先添加它。
无需ORDER BY，因此请将其删除。
从子查询Order_date

SELECT

使用别名
子查询本身就足够了。

SELECT l.Format_id as PRODUCT,   
       COUNT(*) AS AMOUNT 
  FROM order_line_108681091 l
       INNER JOIN order_108681091 o
           ON o.order_id = l.order_id
 WHERE o.Order_Date LIKE '%JAN-14%'
GROUP BY 
       l.Format_id;

Answer 3

根本不需要子查询。而且，我直接在日期使用like时感到非常不舒服。将日期显式转换为字符串：

select ol.Format_id as Product, COUNT(*) AS AMOUNT 
from order_line_108681091 ol Inner Join
     order_108681091 o
     ON o.order_id = ol.order_id
where to_char(o.Order_Date, 'MMM-YYYY') = 'JAN-2014'
group by ol.Format_id
order by count(*) desc;

实际上，如果您在OrderDate上有索引，则可以使用以下内容（以利用索引）：

select ol.Format_id as Product, COUNT(*) AS AMOUNT 
from order_line_108681091 ol Inner Join
     order_108681091 o
     ON o.order_id = ol.order_id
where o.Order_Date >= to_date('2014-01-01', 'YYYY-MM-DD') and
      o.Order_Date < to_date('2014-02-01', 'YYYY-MM-DD')
group by ol.Format_id
order by count(*) desc;

将函数从列移动到常量允许在列上使用索引。

Oracle SQL缺少关键字

3 个答案: