mysql> use  test;
Database changed


mysql> create  table t1(authority   varchar(20));
Query OK, 0 rows affected (0.42 sec)

mysql> create  table t2( id int ,name varchar(20));
Query OK, 0 rows affected (0.32 sec)

mysql> insert  into t1 values(1),(2),(3);
Query OK, 3 rows affected (0.31 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> insert  into t2 values(1,"zhangsan"),(2,"lisi"),(3,"wangwu");
Query OK, 3 rows affected (0.30 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> select * from t2 where id in (select authority from t1);
+------+----------+
| id   | name     |
+------+----------+
|    1 | zhangsan |
|    2 | lisi     |
|    3 | wangwu   |
+------+----------+
3 rows in set (0.03 sec)

------解决方案--------------------
select *
from 第二张表
where id in (select authority from 第一张表)


------解决方案--------------------
贴建表及插入记录的SQL，及要求结果出来看看
SELECT A.* FROM B1 A INNER JOIN B2 B ON A.ID=B.authority

------解决方案--------------------
select *
from table2
where id in (select authority from table1)


------解决方案--------------------
每次来做问答，发现我心中的答案总被一个狼头或者一个苹果上的企鹅说出来了

------解决方案--------------------
select *
from table2
where id in (select authority from table1)
这个就可以的呀

------解决方案--------------------

select * from db_groupuser a inner join db_authority b on find_in_set(b.id,a.authority)>0
这个不行？要求什么结果？