如何在子查询中实现多列过滤

-- 子查询user_id 重复时,不会导致结果重复 
select user_name from qujing where id in (select user_id from user_kills);

-- 使用join时,会重复
select a.user_name from qujing a join user_kills b on a.id =b.user_id;

-- 使用distinct去除重复记录
select distinct a.user_name from qujing a join user_kills b on a.id =b.user_id;

SELECT
    user_id,
    MAX(kills)
FROM
    user_kills
GROUP BY
    user_id

SELECT
    a.user_name,
    b.timestr,
    kills
FROM
    qujing a
JOIN user_kills b ON a.id = b.user_id
WHERE
    (b.user_id, b.kills) IN (
        SELECT
            user_id,
            MAX(kills)
        FROM
            user_kills
        GROUP BY
            user_id
    );