--一、现有学生表student，班级表classInfo，表结构如下：

--student表：sid学号，sname姓名，sex性别，birthday生日，age入学年龄，smoney缴费，cid班级ID

--classInfo表：班级编号cid，班级名称cname

--建表

drop table student cascade constraint;

drop table classinfo cascade constraint;

create table student(

sid number(6) constraint pk_stu_sid primary key,

sname varchar2(20),

sex varchar2(4),

birthday date,

age number(2),

smoney number(7,2),

cid number(4)

);

create table classinfo(

cid number(4) constraint pk_cls_cid primary key,

cname varchar2(20)

);

alter table student add constraint fk_stu_cls_cid foreign key(cid) references classinfo(cid);

insert into classinfo values(1101,'工商管理');

insert into classinfo values(1102,'计算机');

insert into classinfo values(1103,'会计');

insert into classinfo values(1104,'药品');

insert into student values(110001,'小明','男',to_date('1999-9-9','yyyy-mm-dd'),10,11220.50,1103);

insert into student values(110002,'小张','女',to_date('1991-6-9','yyyy-mm-dd'),19,10000.00,1102);

insert into student values(110003,'小红','女',to_date('1996-7-3','yyyy-mm-dd'),14,8800.00,1102);

insert into student values(110004,'张三','男',to_date('1996-2-1','yyyy-mm-dd'),14,6600.00,1102);

insert into student values(110005,'小花','女',to_date('1994-6-7','yyyy-mm-dd'),16,11440.50,1101);

insert into student values(110006,'王五',null,to_date('1991-12-5','yyyy-mm-dd'),20,11440.50,1101);

commit;

select * from student; 

select * from classinfo;

--1、 查询入学年龄在18-20的女生或者未输入性别的学生信息，且年龄小的排在后面。

select * from student where age between 18 and 20 and (sex='女' or sex is null);

--2、 查询班级名称、学生姓名、性别、缴费（要求显示单位：元），相同班级的要放在一起，再按姓名升序排列。

select c.cname,s.sname,s.sex,s.smoney||'元' smoney from student s

join classinfo c on s.cid=c.cid order by c.cname,s.sname;

--3、 查询各班名称和人数。

select cname,count(*) from classinfo c join student s on c.cid=s.cid group by cname;

--4、 查询各班名称和人数，但人数必须不少于2，且人数多的放在前面。

select cname,count(*) from classinfo c join student s on c.cid=s.cid 

group by cname having count(*)>=2 order by count(*) desc;

--5、 查询1980年出生的有哪些学生。

select * from student where to_char(birthday,'yyyy')='1980';

select * from student where to_char(birthday,'yyyy')='1991';

--6、 查询男生和女生人数，没有输入性别的当作男生计算。

select sex,count(*) from (select nvl(sex,'男') sex from student) group by sex;

--7、 查询没有人员的班级。

select * from classinfo where cid not in(select distinct cid from student);

--8、 查询入学年龄在20以上的学生信息。

select * from student where age>20;

select * from student where age>=20;

--9、 查询班级平均入学年龄在20及以上的班级名称和平均年龄。

select * from classinfo c join (select cid,avg(age) avg_age from student group by cid) t 

on c.cid=t.cid where avg_age>=20;

select * from classinfo c join (select cid,avg(age) avg_age from student group by cid) t 

on c.cid=t.cid where avg_age>=15;

--二、现有 

--部门表bm：bid部门编号，bname名称

--人员表ry：rid人员编号，rname名称，bid部门编号

--工资表gz：rid人员编号，sal工资金额，rq发放日期

--建表

drop table bm cascade constraint;

drop table ry cascade constraint;

drop table gz cascade constraint;

create table bm(

bid number(4) constraint pk_bm_bid primary key,

bname varchar2(10)

);

create table ry(

rid number(4) constraint pk_ry_rid primary key,

rname varchar2(20),

bid number(4)

);

create table gz(

rid number(4),

sal number(7,2),

rq date

);

alter table ry add constraint fk_ry_bm_bid foreign key(bid) references bm(bid);

alter table gz add constraint fk_gz_ry_rid foreign key(rid) references ry(rid);

insert into bm values(1001,'销售');

insert into bm values(1002,'后勤');

insert into ry values(1101,'tom',1001);

insert into ry values(1103,'barbie',1001);

insert into ry values(1102,'jim',1002);

insert into gz values(1101,1200.5,sysdate);

insert into gz values(1101,1200.5,sysdate);

insert into gz values(1102,2000,sysdate);

insert into gz values(1103,5000,sysdate);

select * from bm;

select * from ry;

select * from gz;

--1、 查询员工姓名、部门名称和个人总工资。

select r.rname,b.bname,g.sal from bm b join ry r on b.bid=r.bid

join (select rid,sum(sal) sal from gz group by rid) g on g.rid=r.rid;

--2、 查询本月发了2笔以上工资的员工信息。

select * from ry r join 

(select rid,to_char(rq,'yyyy-mm') rq,count(sal) sals from gz group by rid,rq) t

on r.rid=t.rid where t.rq=to_char(sysdate,'yyyy-mm') and sals=2;

--3、 查询各部门的总工资。ry.bid group by bm.bname;

select bname,sum(sal) from bm b join ry r on b.bid=r.bid join gz g on r.rid=g.rid group by bname;

--4、 查询2009年8月份各部门工资最高的员工信息，显示部门名称、员工姓名和员工工资。

select * from

(select b.bid,max(g.sal) sal from bm b join ry r on b.bid=r.bid

join (select rid,to_char(rq,'yyyy-mm') rq,sum(sal) sal from gz group by rid,rq) g on g.rid=r.rid 

group by b.bid,b.bname) t1

join 

(select b.bid,b.bname,r.rid,r.rname,g.sal from bm b join ry r on b.bid=r.bid

join (select rid,to_char(rq,'yyyy-mm') rq,sum(sal) sal from gz group by rid,rq) g on g.rid=r.rid) t2

on

t1.bid = t2.bid and t1.sal=t2.sal;

--一、现有学生表student，班级表classInfo，表结构如下：

--student表：sid学号，sname姓名，sex性别，birthday生日，age入学年龄，smoney缴费，cid班级ID

--classInfo表：班级编号cid，班级名称cname

--1、 把新进的学生Tom，其学号为x009，年龄19，分配到5班。

--insert into student values(009,'tom',null,null,19,null,5);

insert into student values(009,'tom',null,null,19,null,1103);

--2、 把1班的前5个人分到2班。

select * from student;

update student set cid = 1102 

where sid in (select * from (select sid from student where cid=1101 order by sid) where rownum<=5);

select * from student;

--3、 把学生需要的缴费降低5%。

select * from student;

update student set smoney = smoney*0.95;

select * from student;

--4、 删除年龄不满18岁的学生信息。

select * from student;

delete from student where age < 15;

select * from student;

--5、 查询1990年以前出生的有哪些学生。

select * from student where to_char(birthday,'yyyy')<1990;

select * from student where to_char(birthday,'yyyy')<2000;

--6、 查询班级平均入学年龄在20及以上的班级名称和平均年龄。

select * from classinfo c join

(select cid,avg(age) from student group by cid) t

on c.cid=t.cid;

--二、现有

--部门表bm：bid部门编号，bname名称

--人员表ry：rid人员编号，rname名称，bid部门编号

--工资表gz：rid人员编号，sal工资金额，rq发放日期

--要求：用显式事务实现给销售部中工资>5000的员工降薪5%，同时，工资<1000的员工涨薪10%。

--select * from gz;

--update gz set sal=sal*0.95 where rid in (select r.rid from bm b join ry r on b.bid=r.bid join gz g on g.rid=r.rid where sal >2000);

--update gz set sal=sal*1.1 where rid in (select r.rid from bm b join ry r on b.bid=r.bid join gz g on g.rid=r.rid where sal <2000);

--select * from gz;