MySQL删除重复的行

Question

我有一个注释表，其结构如下：

id, name, email, comment

我有很多重复的评论，名字和电子邮件都一样。我需要删除它们，有人可以建议我如何使用一个查询来实现此目标吗？

谢谢

Answer 1

DELETE FROM comments c1

WHERE EXISTS (
    SELECT * 
    FROM comments c2 
    WHERE c2.id <> c1.id 
        AND c2.name = c1.name 
        AND c2.email = c1.email 
        AND c2.comment = c1.comment
)

AND c1.id <> (
    SELECT MIN(c2.id) 
    FROM comments c2 
    WHERE c2.name = c1.name 
        AND c2.email = c1.email 
        AND c2.comment = c1.comment
)