mysql插入的内容被自动截断

表结构中，host字段没有4个字符，插入内容192.168.56.101 ，到入库内容只有192.，刚好长度为4，其它内容被自动截断

mysql> desc disk;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| host  | varchar(4)  | YES  |     | NULL    |       |
| month | int(11)     | YES  |     | NULL    |       |
| size  | int(11)     | YES  |     | NULL    |       |
| ip    | varchar(20) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

mysql> insert into disk (host) values ("192.168.56.101");
Query OK, 1 row affected, 1 warning (0.01 sec)

mysql> select * from disk ;
+------+-------+------+-----------+
| host | month | size | ip        |
+------+-------+------+-----------+
| c    |    18 |  996 | 127.0.0.1 |
| 192. |    18 |  997 | NULL      |
| 192. |  NULL | NULL | NULL      |
+------+-------+------+-----------+
3 rows in set (0.00 sec)