select to_char(sysdate,‘yyyy-mm-dd hh24:mi:ss‘)
select * from tablename where time>= to_date(‘2011-05-02‘,‘yyyy-mm-dd‘)
select * from tablename where to_char(time,‘yyyy-mm-dd‘)>=‘2011-05-02‘ and to_char(time,‘yyyy-mm-dd‘)<=‘2011-05-30‘
原文：http://www.cnblogs.com/kakaisgood/p/7610432.html