DISTINCT或GROUP BY无法正常工作。不知道哪个

Question

我在使用DISTINCT和GROUP BY的查询中仍然遇到问题，但仍收到有关该行的重复行。 GBelow是查询：

SELECT DISTINCT ms.id AS ms_id, ms.identity, ms.timezone, ms.language,
 ms.country, ms.dst, ms.mobile, ms.voice, ms.email,  ms.firstname, ms.lastname, ms.gender, ms.address_1,
 ms.address_2, ms.city, ms.state, ms.zipcode, ms.dateofbirth,
  ms.custom_field_1, ms.custom_field_2, ms.custom_field_3, ms.custom_field_4,
 ms.custom_field_5, ms.carrier, ms.stamp AS ms_stamp,
  ss.id AS ss_id, ss.last_response_text, ss.stamp AS ss_stamp,
 c.id AS c_id, c.name, c.stamp AS c_stamp,
 c.messenger_account, c.keyword, c.community, ms.hash
 FROM tbl_messenger_subscriber_session ss
 JOIN tbl_messenger_subscriber ms ON ss.subscriber = ms.id
 LEFT JOIN tbl_messenger_subscriber_category c ON c.id = ss.subscriber_category
 WHERE ms.custom_field_1 = 'Middlesex' AND ss.subscriber_category IN ('23607','23634')
GROUP BY ms_id, c.messenger_account

并且输出看起来像这样

ms_id   | other columns
1636088 | xxxxxxxxxxxx
1636088 | xxxxxxxxxxxx
1636090 | xxxxxxxxxxxx
1636090 | xxxxxxxxxxxx
1636336 | xxxxxxxxxxxx
1636337 | xxxxxxxxxxxx

预期的输出看起来像这样

ms_id   | other columns
1636088 | xxxxxxxxxxxx
1636090 | xxxxxxxxxxxx
1636336 | xxxxxxxxxxxx
1636337 | xxxxxxxxxxxx

在查询DISTINCT和GROUP BY时，我做错了什么吗？

Answer 1

如果您想每ms_id排一行，则您的代码没有这样做。 SELECT DISTINCT返回all列的唯一组合。

一种执行所需操作的方法使用row_number()：

SELECT x.*
FROM (SELECT . . .,
             ROW_NUBMER() OVER (PARTITION BY ms.id ORDER BY ms.id) as seqnum
      FROM tbl_messenger_subscriber_session ss JOIN
           tbl_messenger_subscriber ms
           ON ss.subscriber = ms.id LEFT JOIN
           tbl_messenger_subscriber_category c
           ON c.id = ss.subscriber_category
      WHERE ms.custom_field_1 = 'Middlesex' AND
           ss.subscriber_category IN ('23607', '23634')
     ) x
WHERE seqnum = 1;