--> 원본테이블 ( 월 , 시작일 , 종료일)  
with t as (
select '1' as mm , 1 as sd , 1 as ed from dual union all
select '2' as col1 , 4 as sd , 6 as ed from dual union all 
select '3' as col1 , 11 as sd , 12 as ed from dual union all 
select '4' as col1 , 24 as sd , 25 as ed from dual union all 
select '5' as col1 , 24 as sd , 29 as ed from dual union all 
select '6' as col1 , 23 as sd , 23 as ed from dual union all 
select '7' as col1 , 2 as sd , 4 as ed from dual union all 
select '8' as col1 , 6 as sd , 11 as ed from dual union all 
select '9' as col1 , 12 as sd , 15 as ed from dual union all 
select '10' as col1 , 17 as sd , 17 as ed from dual union all
select '11' as col1 , 19 as sd , 19 as ed from dual union all
select '12' as col1 , 26 as sd , 29 as ed from dual   
)
select 
    *
    from 
    t

아래는 원본테이블에서 월별로 중복되는 근무일이 있는지 확인하는 쿼리인데 
셀프조인을 이용하였습니다. 혹시 깔끔하게 분석함수를 이용해서 같은결과를 
보여줄수 있나요? 
감사합니다. 

--> 셀프조인과 그룹바이를 이용한 결과 
with t as (
select '1' as mm , 1 as sd , 1 as ed from dual union all
select '2' as col1 , 4 as sd , 6 as ed from dual union all 
select '3' as col1 , 11 as sd , 12 as ed from dual union all 
select '4' as col1 , 24 as sd , 25 as ed from dual union all 
select '5' as col1 , 24 as sd , 29 as ed from dual union all 
select '6' as col1 , 23 as sd , 23 as ed from dual union all 
select '7' as col1 , 2 as sd , 4 as ed from dual union all 
select '8' as col1 , 6 as sd , 11 as ed from dual union all 
select '9' as col1 , 12 as sd , 15 as ed from dual union all 
select '10' as col1 , 17 as sd , 17 as ed from dual union all
select '11' as col1 , 19 as sd , 19 as ed from dual union all
select '12' as col1 , 26 as sd , 29 as ed from dual   
)
select 
    a.mm , a.sd , a.ed , listagg(b.mm ,',')within group (order by to_number(b.mm)) 중복월 
    from 
    t a left outer join t b 
            on a.mm <> b.mm(+) --> 월이 다르고 
            and ( a.sd between b.sd(+) and b.ed(+) or a.ed between b.sd(+) and b.ed(+) ) --> 날짜는 중복
    group by 
        a.mm , a.sd , a.ed