MySQL - 使用Join运算符后重复列 [英] MySQL - Duplicate columns after using Join operator

问题描述

如标题所述，我将使用 JOIN 查询获取重复的列。
给出几个表，我想写select select语句，只需要
从所需表的信息。

As stated in the title, I'm getting duplicate columns with this JOIN query. A few tables are given and I want to write select statements to get only the information from the tables which are needed.

这是我的SQL代码到目前为止：

Here is my SQL code so far:

    SELECT mitarbeiter.PNR, pfleger.PNR, Name
    from pfleger
    JOIN mitarbeiter on (mitarbeiter.PNR=pfleger.PNR)
    where Ort='Frankfurt';

执行后，我得到以下结果：

After executing, I get the following result:

您可以看到问题：我有两个PNR列，我不想拥有。
如何删除重复？我尝试过 SELECT DISTINCT ... ，但没有完成我的目标。

You can see the problem: I have two PNR columns which I don't want to have. How can I remove the duplicate? I have tried SELECT DISTINCT ... but it doesn't accomplish my goal.

推荐答案

正如其他用户已经提到的，您只需从 SELECT 子句中删除一个字段名称。我只是想补充一点，如果你加入的字段在两个表中都有相同的名称，你可以使用特殊的语法，这样可以将这两个列作为一个引用引用：

As other users have already mentioned, you just need to remove a field name from the SELECT clause. I just want to add that if the field you join on has the same name in both tables you can use special syntax, which allows to reference both columns as a single one:

SELECT PNR, Name
from pfleger
JOIN mitarbeiter USING (PNR)
where Ort='Frankfurt';

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