mysql> desc user;
+-----------------------+-----------------------------------+------+-----+---------+-------+
| Field                 | Type                              | Null | Key | Default | Extra |
+-----------------------+-----------------------------------+------+-----+---------+-------+
| Host                  | varchar(60) binary                |      | PRI |         |       |
| User                  | varchar(16) binary                |      | PRI |         |       |
| Password              | varchar(16) binary                |      |     |         |       |
| Select_priv           | enum('N','Y')                     |      |     | N       |       |
| Insert_priv           | enum('N','Y')                     |      |     | N       |       |
| Update_priv           | enum('N','Y')                     |      |     | N       |       |
| Delete_priv           | enum('N','Y')                     |      |     | N       |       |
| Create_priv           | enum('N','Y')                     |      |     | N       |       |
| Drop_priv             | enum('N','Y')                     |      |     | N       |       |
| Reload_priv           | enum('N','Y')                     |      |     | N       |       |
| Shutdown_priv         | enum('N','Y')                     |      |     | N       |       |
| Process_priv          | enum('N','Y')                     |      |     | N       |       |
| File_priv             | enum('N','Y')                     |      |     | N       |       |
| Grant_priv            | enum('N','Y')                     |      |     | N       |       |
| References_priv       | enum('N','Y')                     |      |     | N       |       |
| Index_priv            | enum('N','Y')                     |      |     | N       |       |
| Alter_priv            | enum('N','Y')                     |      |     | N       |       |
| Show_db_priv          | enum('N','Y')                     |      |     | N       |       |
| Super_priv            | enum('N','Y')                     |      |     | N       |       |
| Create_tmp_table_priv | enum('N','Y')                     |      |     | N       |       |
| Lock_tables_priv      | enum('N','Y')                     |      |     | N       |       |
| Execute_priv          | enum('N','Y')                     |      |     | N       |       |
| Repl_slave_priv       | enum('N','Y')                     |      |     | N       |       |
| Repl_client_priv      | enum('N','Y')                     |      |     | N       |       |
| ssl_type              | enum('','ANY','X509','SPECIFIED') |      |     |         |       |
| ssl_cipher            | blob                              |      |     |         |       |
| x509_issuer           | blob                              |      |     |         |       |
| x509_subject          | blob                              |      |     |         |       |
| max_questions         | int(11) unsigned                  |      |     | 0       |       |
| max_updates           | int(11) unsigned                  |      |     | 0       |       |
| max_connections       | int(11) unsigned                  |      |     | 0       |       |
+-----------------------+-----------------------------------+------+-----+---------+-------+

마지막부분을 보면  data type이 blob과 int 입니다. 당연히 계속해서 Y만 집어 넣으면 안돼죠..