Question

我有以下表格

customer
custID | name | address

并且

magazinesubscription
customerID | magazinename | cost | startdate | enddate

newspapersubscription
customerID | newspapername | cost | startdate | enddate

newspaper
newspapername | cost | publishedby

magazine
magazinename | cost | publishedby

现在我想要为每位顾客打印，他们的姓名，地址，他们的杂志订阅，他们的报纸订阅，包括杂志和报纸的名称和出版商以及每个订阅的结束日期。

我尝试过这样做，但它不起作用。

select * from customer
JOIN
(select  customerID, newspapername, enddate, n.publishedby 
 from newspapersubscription ns and newspaper n 
 where published in(select publishedby 
                    from newspaper 
                    where ns.newspapername = n.newspapername)
UNION
select  customerID, magazinename, enddate, m.publishedby 
from magazinesubscription ms and magazine m 
 where published in(select publishedby 
                    from magazine 
                     where ms.newspapername = m.newspapername));

Answer 1

我不确定您要对上述查询做什么。但我可以在您编写的查询中指出错误。

and不是从不同表中获取数据的有效sql关键字。

(select  customerID, newspapername, enddate, n.publishedby 
 from newspapersubscription ns, newspaper n 
 where published in(select publishedby 
                    from newspaper 
                    where ns.newspapername = n.newspapername)
UNION
select  customerID, magazinename, enddate, m.publishedby 
from magazinesubscription ms, magazine m 
 where published in(select publishedby 
                    from magazine 
                     where ms.newspapername = m.newspapername));

获得上述查询的结果后。您无需任何条件即可加入客户表。这将表现为两个表的笛卡尔积，从而组合所有数据。

连接表并编写SQL查询以检索数据

1 个答案: