小群纪

MySQL 的字符集支持(Character Set Support)有两个方面：字符集(Character set)和排序方式(Collation)。对于字符集的支持细化到四个层次: 服务器(server)，数据库(database)，数据表(table)和连接(connection)。
查看系统的字符集和排序方式的设定可以通过下面的两条命令：

mysql> SHOW VARIABLES LIKE 'character_set_%';
+--------------------------+-------------------------------+
| Variable_name            | Value                         |
+--------------------------+-------------------------------+
| character_set_client     | latin1                        |
| character_set_connection | latin1                        |
| character_set_database   | latin1                        |
| character_set_results    | latin1                        |
| character_set_server     | latin1                        |
| character_set_system     | utf8                          |
| character_sets_dir       | D:\var\mysql5\share\charsets\ |
+--------------------------+-------------------------------+

mysql> SHOW VARIABLES LIKE 'collation_%';
+----------------------+-------------------+
| Variable_name        | Value             |
+----------------------+-------------------+
| collation_connection | latin1_swedish_ci |
| collation_database   | latin1_swedish_ci |
| collation_server     | latin1_swedish_ci |
+----------------------+-------------------+

SET CHARACTER SET 'utf8';
相当于：
SET character_set_client = utf8;
SET character_set_results = utf8;

但执行"INSERT"语句时，仍然乱码;

SET NAMES 'utf8';
它相当于下面的三句指令：
SET character_set_client = utf8;
SET character_set_results = utf8;
SET character_set_connection = utf8;