题解 | #删除emp_no重复的记录

-- 删除emp_no重复的记录，只保留最小的id对应的记录
DELETE FROM titles_test
WHERE id NOT IN (
    -- 子查询：选择每个emp_no分组中最小的id
    SELECT min_id FROM (
        SELECT MIN(id) AS min_id
        FROM titles_test
        GROUP BY emp_no
    ) AS t1
);