mysql的字符集乱码问题

Question

最近总是被mysql的乱码困扰，虽然解决了乱码，但是还不不太清楚，各位帮我看看，下面显示的字符集两类，每个都是代表什么意思？在干什么的时候会用到？为什么会出现乱码？我一般是和php连接的,连接php的时候有时候也会出现乱码？
mysql> show variables like 'character_set_%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)mysql> show variables like 'collation_%';
+----------------------+-----------------+
| Variable_name        | Value           |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database   | utf8_general_ci |
| collation_server     | utf8_general_ci |
+----------------------+-----------------+
3 rows in set (0.00 sec)

Answer 1

参考下贴中有关字符集的知识简介。http://blog.csdn.net/ACMAIN_CHM/archive/2009/05/12/4174186.aspx
MySQL 中文显示乱码