sql 删除重复的数据，保留一条，并且保留update_time最大的那条

DELETE
FROM
    t
WHERE
    t.`name` IN (
        SELECT
            t.`name`
        FROM
            (SELECT * FROM t) t
        GROUP BY
            t.`name`
        HAVING
            count(1) > 1
    )
AND t.id NOT IN (
    SELECT
        substring_index(max(t.new_u_time), ',', - 1)
    FROM
        (
            SELECT
                t.id,
                t.`name`,
                t.update_time,
                CONCAT(t.update_time, ',', t.id) new_u_time
            FROM
                t
        ) t
    GROUP BY
        t.`name`
    HAVING
        count(1) > 1
)