ERROR 1267 (HY000): Illegal mix of collations (gbk_chines

mysql> select count(*) from signon_class where class_type='面授';
ERROR 1267 (HY000): Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '='
mysql> set names gbk2312;
ERROR 1115 (42000): Unknown character set: 'gbk2312'
mysql> set names gbk2312
-> ;
ERROR 1115 (42000): Unknown character set: 'gbk2312'
mysql> set names gb2312;
Query OK, 0 rows affected (0.00 sec)
mysql> select count(*) from signon_class where class_type='面授';
+----------+
| count(*) |
+----------+
|      185 |
+----------+
1 row in set (0.00 sec)
mysql>