SQL显示重复值问题

Question

我在我的项目中使用以下查询，但问题重复值正在重复。我也使用了DISTINCT和GROUP BY。请帮帮我。

查询：

SELECT
    dob.user_info.users_id AS user_id,
    CONVERT(
        nvarchar(50),
        dbo.chat_message.time
    ) AS chat_time,
    dbo.user_info.users_name AS user_name
FROM
    dbo.user_info
INNER JOIN
    dbo.chat_message ON dbo.user_info.eve_id = 19
AND dbo.user_info.user_id = dbo.chat_message.user_id
AND dbo.user_info.user_id <> 478 
AND dbo.user_info.user_type <> 'admin' 
AND dbo.chat_message.delete_status = 1 
GROUP BY 
  dbo.user_info.user_id, 
  dbo.user_info.user_name, 
  time

OUTPUT应该像

|505, mothan, Chk, 2015-03-23 10:24:15.000| 
|551,yasar, hi yasar how are you ?, 2015-03-16 16:41:49.000| 
|566, Jegan , hi jegan, 2015-03-16 16:41:07.000| 
|567 , Prabu, hi prabu, 2015-03-16 16:41:07.000|

如果服务器日期等于聊天日期，那么它应该只显示聊天时间。如果服务器日期大于聊天日期，那么它应该显示日期，如24feb。

Answer 1

更新版本：

with cte as 
(
SELECT dob.user_info.users_id AS user_id,
       CONVERT(nvarchar(50), dbo.chat_message.time) AS chat_time,
       dbo.user_info.users_name AS user_name,
       dbo.chat_message.message
FROM
    dbo.user_info
INNER JOIN
    dbo.chat_message ON dbo.user_info.eve_id = 19
AND dbo.user_info.user_id = dbo.chat_message.user_id
AND dbo.user_info.user_id <> 478 
AND dbo.user_info.user_type <> 'admin' 
AND dbo.chat_message.delete_status = 1
)
select * from cte t1
where not exists (select 1 from cte t2
                  where t2.chat_time > t1.chat_time
                    and t2.user_id = t1.user_id)

Answer 2

您有不同的时间字段，因此可以获得多个结果。 如果您将时间字段排除在组外并使用最大值（时间），您将获得结果中的最新时间。

SELECT dob.user_info.users_id AS user_id,
CONVERT(nvarchar(50), MAX(dbo.chat_message.time)) AS chat_time,
dbo.user_info.users_name AS user_name, dbo.chat_message.message FROM dbo.user_info INNER JOIN dbo.chat_message ON dbo.user_info.eve_id = 19 AND dbo.user_info.user_id = dbo.chat_message.user_id AND dbo.user_info.user_id <> 478 AND dbo.user_info.user_type <> 'admin' AND dbo.chat_message.delete_status = 1
GROUP BY dbo.user_info.user_id, dbo.user_info.user_name, dbo.chat_message.message

Answer 3

非常好的问题，如果有效的话，请你试试下面的一个

SELECT
    Distinct dob.user_info.users_id AS user_id,
    CONVERT(
        nvarchar(50),
        dbo.chat_message.time
    ) AS chat_time,
    dbo.user_info.users_name AS user_name
FROM
    dbo.user_info
INNER JOIN
    dbo.chat_message ON dbo.user_info.eve_id = 19
AND dbo.user_info.user_id = dbo.chat_message.user_id
AND dbo.user_info.user_id <> 478 
AND dbo.user_info.user_type <> 'admin' 
AND dbo.chat_message.delete_status = 1 
GROUP BY 
  dbo.user_info.user_id