--分页的sql语句
select * from (select rownum rn,e.* from emp e where rownum<9 order by empno)e where rn>=4;
select * from (select e.* ,rownum rn from (select * from emp) e) where rn>=5 and rn<=15;
其中rn用来指定行号。后面的5和15，可以从前台以入参形式传入，用来指定查询的范围
--删除重复语句
delete from zp z1 where rowid > (select min(rowid) from zp z2 where z1.empno = z2.empno);