oracle显示一个月的所有天数

效率高：

select to_date('200809','yyyymm')+(rownum-1) s_date from dual
connect by rownum<=last_day(to_date('200809','yyyymm')) - to_date('200809','yyyymm')+1

 

效率低：

select
 to_date('200902','yyyymm')+(rownum-1) s_date  
 from all_tables
 where rownum <=
(
 select last_day(to_date('200902','yyyymm')) - to_date('200902','yyyymm')+1 from dual
 )