一个关于高级查询的问题，纠结好久了。表已建好

--创建职员表
create table tbEmp
(
  eID number primary key, --职员编号
  eName varchar2(20) not null, --职员姓名
  eSex varchar2(2) not null --职员性别
  check(esex in ('男','女')),  
  eAge number not null check(eage>=18), --职员年龄
  eAddr varchar2(50) not null, --职员地址
  eTel varchar2(30) not null, --职员电话
  eEmail varchar2(30) --职员邮箱
);

insert into tbemp---------------------
(eID,ename,esex,eage,eaddr,etel)
values
(1,'赵龙','男',25,'湖南省长沙市伍家岭江南苑9栋203号','0731-4230123');
insert into tbemp---------------------
(eID,ename,esex,eage,eaddr,etel)
values
(2,'李云','女',23,'湖南省长沙市东风路东风新村21栋502号','0731-4145268');
insert into tbemp---------------------
(eID,ename,esex,eage,eaddr,etel)
values
(3,'孙一成','男',24,'湖南省株洲市601厂宿舍15栋308号','0732-8342567');
insert into tbemp---------------------
(eID,ename,esex,eage,eaddr,etel)
values
(4,'林笑','男',27,'湖南省郴洲市人民医院20栋301号','0735-2245214');
insert into tbemp---------------------
(eID,ename,esex,eage,eaddr,etel)
values
(5,'卫晴','女',23,'湖南省长沙市望月湖12栋403号','0731-8325124');
--创建商品表
create table tbProd
(
  pID number primary key, --商品编号
  pType varchar2(20) not null, --商品类型
  pMark varchar2(20) not null, --商品品牌
  pSpec varchar2(20)--商品规格  
);
insert into tbprod values(1,'电视机','长虹','29英寸纯平');

insert into tbprod values(2,'电视机','长虹','29英寸纯平艺术');

insert into tbprod values(3,'电视机','长虹','32英寸背投');

insert into tbprod values(4,'电视机','熊猫','29英寸纯平');

insert into tbprod values(5,'电视机','熊猫','29英寸纯平艺术');

insert into tbprod values(6,'电视机','熊猫','32英寸背投');

insert into tbprod values(7,'笔记本','联想','P4-1.8G');

insert into tbprod values(8,'笔记本','联想','P4-2.4G');

insert into tbprod values(9,'笔记本','紫光','P4-1.8G');

insert into tbprod values(10,'笔记本','紫光','P4-2.4G');

--创建销售情况表
create table tbSales
(
  srNO number primary key, --记录编号
  eID number not null references tbemp, --职员编号
  pID number not null references tbprod, --商品编号
  pQty number not null check(pqty>0), --销售数量
  pAmount number(9,2) not null check(pamount>0), --销售价值
  sDate date --销售时间
);
select * from tbemp;
select * from tbprod;
insert into tbsales values(1,1,1,10,21000,'12-3月-2004');

insert into tbsales values(2,1,2,5,20000,to_date('2004-3-12','yyyy-MM-dd'));

insert into tbsales values(3,1,4,12,23500,to_date('2004-3-14','yyyy-MM-dd'));

insert into tbsales values(4,1,5,4,16500,to_date('2004-3-14','yyyy-MM-dd'));

insert into tbsales values(5,2,3,3,31000,to_date('2004-3-11','yyyy-MM-dd'));

insert into tbsales values(6,2,6,4,40000,to_date('2004-3-13','yyyy-MM-dd'));

insert into tbsales values(7,3,7,5,40000,to_date('2004-3-13','yyyy-MM-dd'));

insert into tbsales values(8,3,8,3,36000,to_date('2004-3-14','yyyy-MM-dd'));

insert into tbsales values(9,4,9,6,41500,to_date('2004-3-12','yyyy-MM-dd'));

insert into tbsales values(10,4,10,5,50000,to_date('2004-3-14','yyyy-MM-dd'));

insert into tbsales values(11,1,1,10,21000,to_date('2004-4-12','yyyy-MM-dd'));

insert into tbsales values(12,1,2,5,20000,to_date('2004-4-12','yyyy-MM-dd'));

insert into tbsales values(13,1,4,12,23500,to_date('2004-4-14','yyyy-MM-dd'));

insert into tbsales values(14,1,5,4,16500,to_date('2004-4-14','yyyy-MM-dd'));