Question

我正在尝试找出一个sql语句来删除表中的重复记录，但最多允许10个重复记录。

我可以执行以下查询来查找这些重复项，但我不知道要删除除前10个重复项之外的所有查询：

SELECT 
    ip,
    date,
    count(ip) as count
FROM 
    table 
WHERE 
    date 
        BETWEEN 
            '2012-02-03 00-00-00' 
        AND 
            '2012-02-03 23:59:59' 
group by 
    ip
having 
    count > 10

我不确定这是否可行，有人可以帮助我吗？

Answer 1

试试这个：

delete t2 
from table t2
join (
    SELECT ip, date, (
            select count(*) from 
            table t1 
            where t1.ip = t.ip and t1.date <= t.date and 
                t1.date BETWEEN '2012-02-03 00-00-00' AND '2012-02-03 23:59:59'
        ) as row 
    FROM table t
    WHERE date BETWEEN '2012-02-03 00-00-00' AND '2012-02-03 23:59:59'
) t3 on t2.date = t3.date and t2.ip = t3.ip and t3.row > 10

它使用某种顺序的行编号，请注意，只有当date和ip对是唯一的时，它才会起作用。

从mysql表中删除重复项但允许最多10个

1 个答案: