mysql> create table table1(
    -> id  int primary key,
    -> name  varchar(10),
    -> code int,
    -> del int
    -> );
Query OK, 0 rows affected (0.09 sec)

mysql> insert into table1 value(1,'jia',1,1)  ;
Query OK, 1 row affected (0.28 sec)

mysql> insert into table1 value(2,'jia',1,1)  ;
Query OK, 1 row affected (0.30 sec)

mysql> insert into table1 value(3,'jia',1,0);
Query OK, 1 row affected (0.28 sec)

mysql> select * from table1;
+----+------+------+------+
| id | name | code | del  |
+----+------+------+------+
|  1 | jia  |    1 |    1 |
|  2 | jia  |    1 |    1 |
|  3 | jia  |    1 |    0 |
+----+------+------+------+
3 rows in set (0.00 sec)

mysql> insert into table1 value(1,'jia2',2,1) ;
ERROR 1062 (23000): Duplicate entry '1' for key 'PRIMARY'
mysql> insert into table1 value(2,'jia2',2,1) ;
ERROR 1062 (23000): Duplicate entry '2' for key 'PRIMARY'
mysql> insert into table1 value(3,'jia2',2,1);
ERROR 1062 (23000): Duplicate entry '3' for key 'PRIMARY'
mysql> insert into table1 values(1,'jia2',2,1) ;
ERROR 1062 (23000): Duplicate entry '1' for key 'PRIMARY'
mysql> insert into table1 values(2,'jia2',2,1) ;
ERROR 1062 (23000): Duplicate entry '2' for key 'PRIMARY'
mysql> insert into table1 values(3,'jia2',2,1);
ERROR 1062 (23000): Duplicate entry '3' for key 'PRIMARY'
mysql> insert into table1 values(11,'jia2',2,1) ;
Query OK, 1 row affected (0.06 sec)

mysql> insert into table1 values(12,'jia2',2,1) ;
Query OK, 1 row affected (0.03 sec)

mysql> insert into table1 values(13,'jia2',2,1);
Query OK, 1 row affected (0.03 sec)

mysql> select * from table1;
+----+------+------+------+
| id | name | code | del  |
+----+------+------+------+
|  1 | jia  |    1 |    1 |
|  2 | jia  |    1 |    1 |
|  3 | jia  |    1 |    0 |
| 11 | jia2 |    2 |    1 |
| 12 | jia2 |    2 |    1 |
| 13 | jia2 |    2 |    1 |
+----+------+------+------+
6 rows in set (0.00 sec)

mysql> delete a from table1 a, (
    -> select code from table1 t where not exists (select 1 from table1 where code=t.code and del!=1)
    -> ) b
    -> where a.code=b.code;
Query OK, 3 rows affected (0.08 sec)

mysql> select * from table1;
+----+------+------+------+
| id | name | code | del  |
+----+------+------+------+
|  1 | jia  |    1 |    1 |
|  2 | jia  |    1 |    1 |
|  3 | jia  |    1 |    0 |
+----+------+------+------+
3 rows in set (0.00 sec)

mysql>