以下練習以emp,dept為準進行查詢：
1，查詢出每種工作的平均工資
select job,avg(sal) from emp group by job;
2，查詢出那種工作的工資最高
select job,sal from emp where sal >= all(select sal from emp);
3，查詢出工資最底的經理的名字
select ename,sal from emp where sal <= all(select sal from emp where job='MANAGER') and job='MANAGER';
4，查詢出部門編號為30的部門里面那種工作的平均工資最高
select job, avg(sal) from emp where deptno=30 group by job having(avg(sal)>=all(select avg(sal) from emp where deptno=30 group by job));
5，查詢出名字中帶K的經理
 select * from emp where ename like '%K%' and job='MANAGER';
6，統計出各個部門的各個工作崗位的平均工資
select deptno,job,avg(sal) 平均工資 from emp group by deptno,job;





























declare
 type z_m is table of emp.ename%type index by binary_integer;
 zm z_m;
 itm number;
 begin
   /*<<andy>>
   declare
    type xiec is record(
       en emp.ename%type,
       sal emp.sal%type);
    em xiec;
   begin*/
    select ename into zm from emp;
    itm :=-50;
    for itm in -50..30 loop
     dbms_output.put_line(zm(itm));
     end loop;
     end;
    /*select ename,sal into em.en,em.sal from emp where ezm := &&adcv;
 dbms_output.put_line(zm);
  end;*/