Mysql删除一个字段相同记录，保留ID最小记录

mysql> select * from test1;  
+------+------+  
| id   | c_id |  
+------+------+  
|    1 | 0013 |  
|    2 | 0014 |  
|    3 | 0013 |  
|    4 | 0013 |  
+------+------+  
4 rows in set (0.06 sec)  
   
   
mysql> delete t from test1 t left join  
    ->  (select c_id,min(id) as min_id from test1 group by c_id) t1  
    ->  on t.id=t1.min_id  
    -> where t1.min_id is null;  
Query OK, 2 rows affected (0.06 sec)  
   
mysql> select * from test1;  
+------+------+  
| id   | c_id |  
+------+------+  
|    1 | 0013 |  
|    2 | 0014 |  
+------+------+  
2 rows in set (0.00 sec)