select * from AAA where to_char(a,‘yyyymmdd‘) = to_char(sysdate,‘yyyymmdd‘);select * from AAA where to_char(a,‘yyyymmdd‘) = to_char(sysdate-1,‘yyyymmdd‘);select * from AAA where trunc(a) = trunc(sysdate);select * from AAA where trunc(a) = trunc(sysdate)-1;原文：http://www.cnblogs.com/sun-rain/p/5176983.html