1、第一种：使用b表数据更新a表
update Player as a ,PlayerSet as b
set a.role_id=b.set_value
where a.role_id=b.set_key
2、第二种：也是使用b表数据更新a表，只是方法不一样
update RoleSet set_key=(SELECT name FROM Player where id = RoleSet.set_value);
3、第三种：使用中间表，解决下面错误 Error Code: 1055. Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'xxxxxxx' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by（中文意思大概是：不能对同一张表进行同时读写）
（分享一个小技巧：使用变量增加不重复后缀） set @i:=1;
update Group
SET name=CONCAT(name,'_', (@i:=@i+1))
where name in
(
SELECT a.GroupName
from
(
SELECT name as GroupName
FROM Group
GROUP BY name
HAVING count(*) > 1
) as a
);