MySql查詢根據某些列字段從表中刪除重複的行？

Question

我的表名是啞元，它包含6列其中ID，NAME，TIMESTAMP和其他3列。

我想刪除ID，NAME和TIMESTAMP值與另一行匹配的重複行。如果有多個具有相同ID，NAME和TIMESTAMP值的行，則保留一個並刪除其他行。

Answer 1

下面是解

https://stackoverflow.com/a/5016434

另一種可能的解決方案，我剛剛碰到：

DELETE n1 FROM names n1, names n2 WHERE n1.id > n2.id AND n1.name = n2.name 

如果你想保持與價值或

最低ID行

DELETE n1 FROM names n1, names n2 WHERE n1.id < n2.id AND n1.name = n2.name 

https://stackoverflow.com/a/5770309

DELETE DupRows.* 
FROM MyTable AS DupRows 
    INNER JOIN (
     SELECT MIN(ID) AS minId, col1, col2 
     FROM MyTable 
     GROUP BY col1, col2 
     HAVING COUNT(*) > 1 
    ) AS SaveRows ON SaveRows.col1 = DupRows.col1 AND SaveRows.col2 = DupRows.col2 
     AND SaveRows.minId <> DupRows.ID; 

Answer 2

這是一個示例代碼。這將幫助你完成它。

DELETE duplicate_rows.* 
FROM dummy AS duplicate_rows 
    INNER JOIN (
     SELECT MIN(id) AS id, name, timestamp 
     FROM dummy 
     GROUP BY session_id, user_id, category_id 
     HAVING COUNT(*) > 1 
    ) AS unique_rows 
ON unique_rows.session_id = duplicate_rows.session_id 
AND unique_rows.user_id = duplicate_rows.user_id 
AND unique_rows.category_id = duplicate_rows.category_id 
AND unique_rows.id <> duplicate_rows.id; 

更詳細的解釋，你在這裏找到：http://mildcoder.com/delete-duplicate-rows-from-a-mysql-table/