SQL内连接 左连接 右连接 怎么让一列特定隐藏啊，恳求大神指点下新手。

Question

两个表store_inforation      and      geography     此表数据在图片

问题：连接Store_Information 表格与Geography表格，实现各区域各店铺销售情况，只显示两表出现共同store_name的记录（region_name,store_name,Sales )

我的答案

select A1.region_name region_name, sum(A2.Sales)Sales from geography A1, Store_information A2 where A1.store_name = A2.store_name group by A1.region_name; 

将此代码运行完没有store_name  !!!

问题2：同上，但要以内连接语法实现

select A1.region_name region_name, sum(A2.Sales) Sales from geography A1 inner join store_information A2 on A1.store_name = A2.store_name group by A1.region_name;

将此代码运行完没有store_name  !!!

问题3：##连接Store_Information 表格与Geography 表格，实现各区域各店铺销售情况，左表全显示，右表只显示store_name在左表出现的记录（region_name ,store_name,Sales )

select*from geography A1 left join store_information A2 on A1.store_name = A2.store_name;

此代码多出了Date不知道如何隐藏 

右连接也同样的问题 。。。。。。。崩溃了     ，，，，求大神   

 

 

Answer 1

select A1.region_name region_name,A1.store_name, sum(A2.Sales)Sales from geography A1, Store_information A2 where A1.store_name = A2.store_name group by A1.region_name,A1.store_name;