select * from dt where dw_data=to_date(to_char(sysdate-1,'YYYY-MM-DD'),'YYYY-MM-DD')  ---取前一天日期SQL>  select * from dt where dw_data=trunc(sysdate-1,'dd');DW_DATA---------25-DEC-00SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';SQL> select trunc(sysdate) from dual; TRUNC(SYSDATE)-------------------2000-12-26 00:00:00SQL> select trunc(sysdate,'dd') from dual;TRUNC(SYSDATE,'DD')-------------------2000-12-26 00:00:00SQL>  select sysdate from dual;SYSDATE-------------------2000-12-26 19:42:39SQL> select * from dt;DW_DATA-------------------2000-12-25 00:00:00