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对mysql Illegal mix of collations(gbk_chinese_ci,IMPLICIT) and (gb2312_chinese_ci,I的解决
对于常见的乱码问题，有的在数据库本身已经为gbk或gb2312时候，但是查询出来却是乱码，这是因为mysql在连接的过程中还有道编码，因此将连接的编码设为gb2312或utf-8
即可，如：
jdbc:mysql://localhost:3306/ipanel?useUnicode=true&characterEncoding=UTF-8
hibernate和jdbc的参数设置是不一样，但大体相同，网上类似的资料很多。
最重要的是这个问题：
Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (gb2312_chinese_ci,IMPLICIT) for operation '='
相信有很多人碰到，意思是说字符编码不一样，不能进行比较，也就是说数据库内部的编码都不一样，有的数据是
gbk_chinese_ci,有的数据是gb2312_chinese_ci，因此解决此问题的核心就是将数据库所有的编码进行统一。
进入命令行模式，
如果MySQL数据库已经安装好，可以使用下列SQL命令查看MySQL当前的字符集设置：
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 | /usr/share/mysql/charsets/ | +--------------------------+----------------------------+ 7 rows in set (0.00 sec) mysql> SHOW VARIABLES LIKE 'collation_%'; +----------------------+-------------------+ | Variable_name | Value | +----------------------+-------------------+ | collation_connection | latin1_swedish_ci | | collation_database | latin1_swedish_ci | | collation_server | latin1_swedish_ci | +----------------------+-------------------+ 3 rows in set (0.00 sec)
依次执行：
set character_set_client =gb2312; set character_set_connection =gb2312; set character_set_database =gb2312; set character_set_results =gb2312; set character_set_server =gb2312; set character_set_system =gb2312; --此处utf-8也可以
然后执行：
SET collation_server = gb2312_chinese_ciSET collation_database = gb2312_chinese_ciSET collation_connection =gb2312_chinese_ci
执行完之后，请检查mysql下每个数据库，表，字段是否都是gb2312，不是则改过来，这样子就不会出现
Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (gb2312_chinese_ci,IMPLICIT) for operation '='
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