select * from stu where stuage is null；select * from stu where null is null;select * from dual where null is not null;select * from dual where null is null;select sysdate from dual;select to_char(sysdate,'yyyy-mm-dd') today from dual;select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') now from dual;
阅读(1283) | 评论(0) | 转发(0) |
