题解 | #删除emp_no重复的记录#

DELETE FROM titles_test  
WHERE NOT EXISTS (  
    SELECT 1  
    FROM (  
        SELECT emp_no, MIN(ID) as min_id  
        FROM titles_test  
        GROUP BY emp_no  
    ) as subquery  
    WHERE subquery.emp_no = titles_test.emp_no AND subquery.min_id = titles_test.ID  
);