（2）列出emp表中各部门job为'CLERK'的员工的最低工资，最高工资
select max(sal) as 最高工资,min(sal) as 最低工资,deptno as 部门号 from emp where job = 'CLERK' group by deptno;
18.根据下面的代码，String s = null ，会抛出NullPointerException;异常的有（A、C）
A：if((s!=null)&(s.length()>0))
B：if((s!=null)&&(s.length()>0))
C：if((s==null)|(s.length()==0))
D：if((s==null)||(s.length()==0))
select
p.id,p.pid,p.name,p.moduleUrl,p.operationalUrl,p.orderNo,p.createTime
from
tbl_permission p
where id in
(select
permission_id
from
tbl_role_permission_relation
where role_id in
(select
role_id
from
tbl_user_rol;e_relation
where
uer_id=#{useId}))
order by p.orderNo
select
tt.*
from(
select * ,rownum as linenum
from (业务SQL)t
where rownum<=pagesize*pageNo-1)tt
where linenum>(pageNo-1)*pagesize