MSQL Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (utf8_general_ci,SYSCONST) for operation 'UNION' 错误解决办法

主要是表编码问题

1.修改表编码：

ALTER TABLE `category` DEFAULT CHARACTER SET utf8 COLLATE utf8_bin; //将一个表category的编码改为utf8

2.修改字段的编码： 

ALTER TABLE `test` CHANGE `dd` `dd` VARCHAR( 45 ) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL