根据单个不同的列选择唯一的行 [英] select unique rows based on single distinct column

问题描述

我想选择具有不同电子邮件的行，请参阅下面的示例表:

I want to select rows that have a distinct email, see the example table below:

+----+---------+-------------------+-------------+
| id | title   | email             | commentname |
+----+---------+-------------------+-------------+
|  3 | test    | [e-mail]   | rob         |
|  4 | i agree | [e-mail]   | rob         |
|  5 | its ok  | [e-mail]   | rob         |
|  6 | hey     | [e-mail]   | rob         |
|  7 | nice!   | [e-mail] | simon       |
|  8 | yeah    | [e-mail]  | john        |
+----+---------+-------------------+-------------+

想要的结果是:

+----+-------+-------------------+-------------+
| id | title | email             | commentname |
+----+-------+-------------------+-------------+
|  3 | test  | [e-mail]   | rob         |
|  7 | nice! | [e-mail] | simon       |
|  8 | yeah  | [e-mail]  | john        |
+----+-------+-------------------+-------------+

我不在乎返回哪个 id 列值.所需的 SQL 是什么?

Where I don't care which id column value is returned. What would be the required SQL?

推荐答案

TSQL 中的快速一键

Quick one in TSQL

SELECT a.*
FROM emails a
INNER JOIN 
  (SELECT email,
    MIN(id) as id
  FROM emails 
  GROUP BY email 
) AS b
  ON a.email = b.email 
  AND a.id = b.id;

这篇关于根据单个不同的列选择唯一的行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！