Question

我相信stackoverflow已经有了答案，但我找不到合适的关键字。所以请帮忙。

表销售如下所示：

state  | sales-representative        | product | sales
NY     | Mike B.                     | prod-A  | 90
FL     | David J.                    | prod-B  | 120 
FL     | Mike B.                     | prod-A  | 15

我需要获得此类销售代表的总销售额。 Mike B.的预期结果看看：

state  | product | sales
NY     | prod-A  | 90
FL     | prod-A  | 15
NY     | prod-B  | 0 <--How can I get this record as well?
FL     | prod-B  | 0

常规总和查询返回前2个记录。我怎样才能获得最后2条记录？

 select state, product, sum(sales) 
      from sales 
      where sales-representative = 'Mike B.' 
       group by state, product

Answer 1

SELECT ss.state, sp.product, SUM(sr.sales)
FROM (SELECT DISTINCT state FROM sales) AS ss
CROSS JOIN (SELECT DISTINCT product FROM sales) AS sp
LEFT JOIN sales AS r  
   AS sr ON ss.state = s.state 
         AND sp.product = s.product
         AND r.`sales-representative` = 'Mike B.'
GROUP BY ss.state, sp.product;

交叉连接可以为您提供州和产品的每种组合，左连接可以获得指定代表的相关销售。

Answer 2

您可以在子查询上使用左连接来表示陈述和产品

   select t.state, t.product, sum(sales)
   from table1 
   left join (
    select t1.state, t2.product
    from t1 
    cross join  (
        select product 
        from t1
    ) t2

   ) t on t.state = table1.state and t.product = table1.product
   grooup by t.state, t.product

Mysql左连接样式sum（）

2 个答案: