表字段字符集校验的差异造成表无法关联

查询：SELECT COUNT(*) FROM `unicode_ci` a,`qwifi.general_ci` b WHERE a.`username` = b.`username` LIMIT 0, 1000

错误代码： 1267
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='

解决办法：修改字符集校验码
 ALTER TABLE `radius`.`radcheck` MODIFY username VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_general_ci;