oracle一个月多少周

with t as(select date'2019-1-1'+level-1 dt from dual connect by level<=365)

select dt,to_char(dt,'w')w,to_char(dt,'day') d,

trunc((to_char(dt,'dd')+to_char(last_day(add_months(dt,-1)),'d')-2) /7)+1 e from t;