汇总查询在列上有连接和计算？

Question

我有汇总查询

char[] c = guess.toCharArray();
for (c : chars) {
   charCount[c] -= 1;
   if (charCount[c] < 0) {
     return 0;
   }
}

它返回最后一行NULL值不会给出总和善解决这个为什么我得到总无效

Actualy我正在使用连接和计算获得记录，如itemprice减去折扣，并按数量乘以现在在计算领域应用ROLLUP

Answer 1

您需要select中的聚合函数：

Select (CASE WHEN (GROUPING(p. product_name ) = 1) THEN 'Total'
             ELSE p.product_name
        END) AS ProductName,
      sum((o.item_price - o.discount_amount )*o.quantity) as Total_Amount  
from products p inner join 
     order_items o
     on o.product_id  = p.product_id
group by p.product_name with rollup;