Oracle檢索12個月

從oracle中檢索12個月出來，做報表經常用得到，一個年度的12個月的數據，爲了防止他一天的數據也沒有。只好用12個月固定的去左連接。
所以取12個月出來

select lpad(level,2,0) from dual
connect by level<13 

至於怎麼左連接，拿出一個例子來先放到這裏

select * from  (select lpad(level,2,0) month from dual 
connect by level<13 ) q,
(select SUBSTR(cbrq,0,6) nd ,sum(ygzdl) from v_zsb_bds_yddl a
inner join t_xtwh_bds_jld b
on a.bjbh = b.bdsckbm
inner join t_xtwh_zsdj_jld c
on b.jldbm = c.jldbm
inner join t_xtwh_zsdj_jbxx d
on c.zsdjid = d.billid

where d.billid ='' and SUBSTR(cbrq,0,4) = ''
group by SUBSTR(cbrq,0,6)
order by SUBSTR(cbrq,0,6) ) b
where  q.month = SUBSTR(b.nd(+),4,2)
order by q.month