问题描述：[HY000][1267] Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8mb4_0900_ai_ci,IMPLIC for operation  ‘=‘

 出现这种问题就是关联表的字符集不匹配

1.查看数据库的字符集

show variables where Variable_name like ‘collation%‘;
结果：

 2.查看关联表字符集

show create table table_name;

3.给关联表设置字符编码

alter table table_name default character set utf8mb4 collate=utf8mb4_general_ci;

4.给关联表字段设置字符编码

ALTER TABLE table_name convert to CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

[HY000][1267] Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8mb4_0900_ai_ci,IMPLIC mysql表字符集不匹配