一次开发过程中遇到一个问题：由于同一个openID对应的不同类型的userID不正确，所以需要改成一样的。

编写逻辑：

①先查询类型为5002的openID,得到需要修改的数据

②根据便利得到的openID，查询类型5001的userID

③根据openID修改相应openID且类型为5002的数据

函数如下：

CREATE DEFINER=`root`@`localhost` PROCEDURE `updatePhone`()
BEGIN
    -- 定义变量
  DECLARE done INT DEFAULT FALSE;
    DECLARE openId  varchar(32);
    DECLARE userID  varchar(32);
    DECLARE userID1  varchar(32);
    DECLARE openList CURSOR FOR select DISTINCT open_id from authorization_record where auth_type = '5002';
    -- 游标中的内容执行完后将done设置为true
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = true;
    OPEN openList; 
    read_loop : LOOP
            FETCH openList INTO openId;
            -- 判断是否结束循环，一定要放到FETCH之后，因为在fetch不到的时候才会设置done为true
            -- 如果放到fetch之前，先判断done，这个时候done的值还是之前的循环的值，因此就会导致循环一次
            IF done THEN
                    LEAVE read_loop;
            END IF;
        
            --  执行SQL操作
            
            SELECT distinct a.user_id INTO userID FROM authorization_record a WHERE a.open_id = CONVERT(openId USING utf8) COLLATE utf8_unicode_ci AND a.auth_type = '5001';
            -- GROUP BY a.open_id;
            
            -- SELECT t.user_id INTO userID1 FROM ( SELECT a.user_id FROM authorization_record a WHERE a.open_id = openId AND a.auth_type = '5001' GROUP BY a.open_id ) t ;
            
            IF userID != '' THEN
                UPDATE authorization_record SET user_id = CONVERT(userID USING utf8) COLLATE utf8_unicode_ci WHERE open_id = CONVERT(openId USING utf8) COLLATE utf8_unicode_ci AND auth_type = '5002';
                COMMIT;
            END IF;
    END LOOP read_loop;
    -- 释放游标
    CLOSE openList;
END;