with table1(id,iid) as(
select 1,'A,B' from dual
union all select 2,'B,C,D' from dual
union all select 3,'A,D' from dual
),
table2(id,mc) as(
select 'A','this is a' from dual
union all select 'B','this is b' from dual
union all select 'C','this is c' from dual
)
select * from table2
where exists(
select 1 from table1 where table1.id=1--此处传你的id
 and instr('%,'||iid||',%',','||table2.id||',')>0);
/*
I MC                                                                            
- ---------                                                                     
A this is a                                                                     
B this is b  
*/