mysql中一次字符集和排序规则引起的sql查询报错

先看sql

  o.city_name             AS '城市',
  o.city_code             AS '城市编码',
  o.comp_name             AS '公司',
  o.comp_code             AS '分公司编码',
  b.brand_name            AS '品牌',
  a.account_code          AS '被处罚系统号',
  l.occur_time            AS '处罚发生日期',
  l.penalize_time         AS '处罚最终判罚日期',
  l.create_time           AS '处罚数据导入时间',
  l.violation_behavior    AS '违规行为名称',
  l.reason                AS '事件描述',
  l.ryb_category          AS '红黄线',
  l.add_score             AS '分值',
  l.credit_score_log_type AS '类别'
FROM credit.credit_account a RIGHT JOIN credit.credit_score_log l ON l.credit_account_id = a.id
  LEFT JOIN credit.org o ON o.comp_code = l.comp_code
  LEFT JOIN credit.brand_comp b ON b.comp_code = o.comp_code.user_credit_score_log u ON u.user_code = a.account_code;

　　

报错提示：[HY000][1267] Illegal mix of collations (utf8mb4_unicode_ci,IMPLICIT) and (utf8mb4_general_ci,IMPLICIT) for operation '='

怀疑是 字符集 或者 排序规则 对应不上，于是通过mysql指令排查下字符集

SHOW FULL COLUMNS FROM credit.credit_account;
SHOW FULL COLUMNS FROM credit.org;
SHOW FULL COLUMNS FROM credit.credit_score_log;
SHOW FULL COLUMNS FROM credit.brand_comp;

　　

credit_account表，org表，credit_score_log表，brand_comp表 四张表字符集分别如下：

经过分析发现 最后一张表 brand_comp 的varchar字段Collation 是  utf8mb4_unicode_ci，前三张表varchar字段段Collation 都是 utf8mb4_general_ci

于是更改表的字符集和排序规则，命令如下

ALTER TABLE brand_comp CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

　　此时再查询最后一张表

排序规则更改后，再执行sql，完美运行，问题解决！