如何从 SQL 中的连接中删除重复的列

我有以下代码

SELECT *
FROM
    customer
INNER JOIN (
    SELECT
        customerid, newspapername, enddate, n.publishedby
    FROM
        newspapersubscription ns,
        newspaper n
    WHERE
        publishedby IN (
            SELECT publishedby
            FROM newspaper
            WHERE ns.newspapername = n.NewspaperName
        )
    UNION
    SELECT
        customerid, Magazinename, enddate, m.publishedby
    FROM
        magazinesubscription ms,
        magazine m
    WHERE
        publishedby IN (
            SELECT publishedby
            FROM magazine
            WHERE ms.Magazinename = m.MagazineName
        )
) ON
    customer.customerid = customerid
ORDER BY
    customer.customerid;

客户表有以下内容：

 customerid | customername | customersaddress

该查询返回以下结果：

customerid | customername | customersaddress | customerid | newspapername | enddate| publishedby

我真正想要的是

customerid | customername | customersaddress | newspapername | magazinename | enddate| publishedby

此处，如果存在杂志名称，则报纸名称字段应为空，反之亦然。此外，联合操作中的 customerid 重复字段不应出现，而在我的结果中，报纸名称和杂志名称的值都放在报纸名称标题下。

我怎样才能做到这一点？

由于您使用“*”查询表，因此您将始终获得两个表中的所有列。为了省略此列，您必须手动命名您想要查询的所有列。为了满足您的其他需求，您只需向联合查询中的每个子句插入一个虚拟列。下面是一个示例，应该可以满足您的需求 -

SELECT customer.customerid, customer.customername, customer.customeraddress, newspapername, magazinename, enddate, publishedby 
FROM customer
INNER JOIN
(select  customerid, newspapername, null Magazinename, enddate, n.publishedby 
 from newspapersubscription ns, newspaper n 
 where publishedby in(select publishedby 
                    from newspaper 
                    where ns.newspapername = n.NewspaperName)
UNION
select  customerid, null newspapername, Magazinename, enddate, m.publishedby 
from magazinesubscription ms, magazine m 
 where publishedby in(select publishedby 
                    from magazine 
                     where ms.Magazinename = m.MagazineName))
on customer.customerid = customerid
ORDER BY customer.customerid;