Question

我想删除AUTHORS_CONVERSATION列中的重复行。

我的代码是：

SELECT AUTHORS.AUTHORS_PHOTO, 
       AUTHORS.AUTHORS_ID, 
       AUTHORS.AUTHORS_NAME, 
       AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID, 
       AUTHORS_MESSAGES.AUTHORS_SENDER_ID,
       AUTHORS_MESSAGES.MESSAGE_CONTENT,
       AUTHORS_MESSAGES.MESSAGE_DATE,
       AUTHORS_MESSAGES.CONVERSATION_ID,
       AUTHORS_MESSAGES.MESSAGE_STATUS
FROM AUTHORS_MESSAGES 
INNER JOIN AUTHORS 
    ON AUTHORS_MESSAGES.AUTHORS_SENDER_ID = AUTHORS.AUTHORS_ID
    OR AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID = AUTHORS.AUTHORS_ID 
WHERE AUTHORS.AUTHORS_ID = 1555 
ORDER BY MESSAGE_DATE DESC;

结果示例：

AUTHORS_ID, AUTHORS_CONVERSATION
1555, 1
AUTHORS_ID, AUTHORS_CONVERSATION
1555, 1
AUTHORS_ID, AUTHORS_CONVERSATION
1555, 1
AUTHORS_ID, AUTHORS_CONVERSATION
1555, 4

应该结果：

AUTHORS_ID, AUTHORS_CONVERSATION
1555, 1
AUTHORS_ID, AUTHORS_CONVERSATION
1555, 4

如果重复，我如何仅按 DATE 显示最后结果排序？谢谢！

Answer 1

我目前无法尝试此查询......但请尝试让我知道

SELECT AUTHORS.AUTHORS_PHOTO, 
   AUTHORS.AUTHORS_ID, 
   AUTHORS.AUTHORS_NAME, 
   AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID, 
   AUTHORS_MESSAGES.AUTHORS_SENDER_ID,
   AUTHORS_MESSAGES.MESSAGE_CONTENT,
   AUTHORS_MESSAGES.MESSAGE_DATE,
   AUTHORS_MESSAGES.CONVERSATION_ID,
   AUTHORS_MESSAGES.MESSAGE_STATUS
FROM (SELECT AUTHORS.AUTHORS_PHOTO, 
   AUTHORS.AUTHORS_ID, 
   AUTHORS.AUTHORS_NAME, 
   AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID, 
   AUTHORS_MESSAGES.AUTHORS_SENDER_ID,
   AUTHORS_MESSAGES.MESSAGE_CONTENT,
   AUTHORS_MESSAGES.MESSAGE_DATE,
   AUTHORS_MESSAGES.CONVERSATION_ID,
   AUTHORS_MESSAGES.MESSAGE_STATUS ,ROW_NUMBER () OVER (PARTITION BY  AUTHORS_CONVERSATION ORDER BY MESSAGE_DATE DESC) AS RowNumber FROM AUTHORS_MESSAGES 
INNER JOIN AUTHORS 
ON AUTHORS_MESSAGES.AUTHORS_SENDER_ID = AUTHORS.AUTHORS_ID
OR AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID = AUTHORS.AUTHORS_ID 
WHERE AUTHORS.AUTHORS_ID = 1555 
ORDER BY MESSAGE_DATE DESC) AS a
WHERE a.RowNumber = 1

Answer 2

你试过按ID分组吗？

示例：

WHERE AUTHORS.AUTHORS_ID = 1555， GROUP BY AUTHORS_ID;

如果你只想要的话，为什么你要在DATE之前订购 AUTHORS_ID和AUTHORS_CONVERSATION？

Answer 3

; WITH CTE AS(
    SELECT 
        AUTHORS.AUTHORS_PHOTO, 
        AUTHORS.AUTHORS_ID, 
        AUTHORS.AUTHORS_NAME, 
        AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID, 
        AUTHORS_MESSAGES.AUTHORS_SENDER_ID,
        AUTHORS_MESSAGES.MESSAGE_CONTENT,
        AUTHORS_MESSAGES.MESSAGE_DATE,
        AUTHORS_MESSAGES.CONVERSATION_ID,
        AUTHORS_MESSAGES.MESSAGE_STATUS,
        ROW_NUMBER() OVER (PARTITION BY AUTHORS_ID, CONVERSATION_ID ORDER BY MESSAGE_DATE DESC) AS RN
    FROM AUTHORS_MESSAGES 
    INNER JOIN AUTHORS 
        ON AUTHORS_MESSAGES.AUTHORS_SENDER_ID = AUTHORS.AUTHORS_ID
        OR AUTHORS_MESSAGES.AUTHORS_RECEIVER_ID = AUTHORS.AUTHORS_ID 
    WHERE AUTHORS.AUTHORS_ID = 1555 
    ORDER BY MESSAGE_DATE DESC;
) SELECT * FROM CTE 
WHERE RN = 1

假设您需要按AUTHORS_ID，CONVERSATION_ID排序重复行，并按MESSAGE_DATE排序。如果不同，请修改 PARTITOIN和ORDER部分

Answer 4

如果您试图避免某些x，y，z列的重复，请在这些列上保留一个组。

按日期删除重复的行

4 个答案: