oracle trunc(sysdate ,'dd') 日期

http://www.blogjava.net/gddg/archive/2007/09/19/146591.html

select trunc(sysdate ,'dd') from dual ;   --  2007-9-19

select trunc(sysdate ,'yyyy') from dual ;   --2007-1-1

select trunc(sysdate ,'mm') from dual ;   --2007-9-1