mysql> select `books`.*, `csessioninfo`.`user_info` from `books` inner join `csessioninfo` on `books`.`openid` = `csessioninfo`.`open_id`
-> ;
ERROR 1267 (HY000): Illegal mix of collations (utf8mb4_0900_ai_ci,IMPLICIT) and (utf8mb4_unicode_ci,IMPLICIT) for operation "="the books table reported an error. How can I change the collation to utf8mb4_unicode_ci??
if you are modifying the character set of a table, use this to try
alter table books convert to character set utf8mb4_unicode_ci;
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