SQL语句判断是否为今天或昨天

方法一
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');

方法二

select * from AAA where trunc(a) = trunc(sysdate);
select * from AAA where trunc(a) = trunc(sysdate)-1;

来源  http://bbs.csdn.net/topics/390972038?page=1