题解 删除emp_no重复的记录，只保留最小的id对应的记录

with t as(
    select min(id)
    from titles_test
    group by emp_no
)    /*不能边查询边删除，需要先创建临时表*/

delete from titles_test
where id not in(select * from t); /*必须有分号

删除语句：
delete from tablename
where condition
*/