1、先查询emp_no对应的最小id
select emp_no,min(id) from titles_test group by emp_no;2、从titles_test 表中删除id 不在1 表范围内的全部信息
delete from titiles_test where id not in (select id from (select emp_no,min(id) from titles_test group by emp_no)as a);
select emp_no,min(id) from titles_test group by emp_no;2、从titles_test 表中删除id 不在1 表范围内的全部信息
delete from titiles_test where id not in (select id from (select emp_no,min(id) from titles_test group by emp_no)as a);