数据库第八周实验——第五章课后题
假设有下面两个关系模式：
职工（职工号，姓名，年龄，职务，工资，部门号）， 其中职工号为主码；
部门（部门号，名称，经理名，电话），其中部门号为主码。
用 SQL 语言定义这两个关系模式，要求在模式中完成以下完整性约束条件的定义：
（1）定义每个模式的主码；
（2）定义参照完整性；
（3）定义职工年龄不得超过60岁
create table Dep
(
Dnum int primary key,
Dname char(10),
Djlname char(10),
Dtel char(20)
);
create table Staff
(
Snum char(10) primary key,
Sname char(10),
Sage int,
constraint C1 check (Sage<=60),
Swjob char(10),
Ssalary char(10),
Sdnum int
foreign key(Sdnum) references Dep(Dnum)
);
对学生-课程数据库编写存储过程， 完成下述功能：
（1）统计离散数学的成绩分布情况，即按照各分数段统计人数。
标准SQL
create procedure divide_grade()
as
declare score_90_100 int;
declare score_80_90 int;
declare score_70_80 int;
declare score_60_70 int;
declare score_0_60 int;
declare score int;
set score_90_100:=
(select count(*) from SC where Grade>=90 and Cno=
(select Cno from Course where Cname='离散数学'));
set score_80_90:=
(select count(*) from SC where Grade>=80 and Grade<90 and Cno=
(select Cno from Course where Cname='离散数学'));
set score_70_80:=
(select count(*) from SC where Grade>=70 and Grade<80 and Cno=
(select Cno from Course where Cname='离散数学'));
set score_60_70:=
(select count(*) from SC where Grade>=60 and Grade<70 and Cno=
(select Cno from Course where Cname='离散数学'));
set score_0_60:=
(select count(*) from SC where Grade>=0 and Grade<60 and Cno=
(select Cno from Course where Cname='离散数学'));
select score_90_100 as '[90,100]', --显示
score_80_90 as '[80,90)',
score_70_80 as '[70,80)',
score_60_70 as '[60,70)',
score_0_60 as '[0,60)';
或者
create procedure divide_rank
as
declare score_90_100 int,
score_80_90 int,
score_70_80 int,
score_60_70 int,
score_0_60 int,
score int;
select score_90_100=count(*) from SC,Course where SC.Cno=Course.Cno and Grade>=90 and Grade<=100 and Cname='离散数学' ;
select score_80_90 =count(*) from SC,Course where SC.Cno=Course.Cno and Grade>=80 and Grade<90 and Cname='离散数学' ;
select score_70_80 =count(*) from SC,Course where SC.Cno=Course.Cno and Grade>=70 and Grade<80 and Cname='离散数学' ;
select score_60_70 =count(*) from SC,Course where SC.Cno=Course.Cno and Grade>=60 and Grade<70 and Cname='离散数学' ;
select score_0_60 =count(*) from SC,Course where SC.Cno=Course.Cno and Grade>=0 and Grade<60 and Cname='离散数学' ;
select score_90_100 as '[90,100]', --显示
score_80_90 as '[80,90)',
score_70_80 as '[70,80)',
score_60_70 as '[60,70)',
score_0_60 as '[0,60)';
T-SQL
--建立离散数学统计表：
create table LiSan
(
Score char(20), --成绩的分段
Count int --人数
);
--存储过程
if (exists(select * from sys.objects where name='Grade_distribution'))
drop procedure Grade_distribution
go
create procedure Grade_distribution
@Cname char(10)
as
declare --定义变量
@less60 int,
@Grade_60_69 int,
@Grade_70_79 int,
@Grade_80_89 int,
@Grade_90_100 int,
@CNO char(10);
begin
select @CNO=Cno from Course where Cname=@Cname;
if @CNO is null
begin
print '不存在+@Cname+课程'
rollback; --回滚事务
return;
end;
select @less60=count(*) from SC where Grade<60 and Cno=@CNO;
select @Grade_60_69=count(*) from SC where Grade>=60 and Grade<70 and Cno=@CNO;
select @Grade_70_79=count(*) from SC where Grade>=70 and Grade<80 and Cno=@CNO;
select @Grade_80_89=count(*) from SC where Grade>=80 and Grade<90 and Cno=@CNO;
select @Grade_90_100=count(*) from SC where Grade>=90 and Grade<=100 and Cno=@CNO;
end;
update LiSan set Count=@less60 where Score='[0,60):';
update LiSan set Count=@Grade_60_69 where Score='[60,69]:';
update LiSan set Count=@Grade_70_79 where Score='[70,79]:';
update LiSan set Count=@Grade_80_89 where Score='[80,89]:';
update LiSan set Count=@Grade_90_100 where Score='[90,100]:';
--执行存储过程
EXEC Grade_distribution
@Cname='离散数学';
（2）统计任意一门课的平均成绩。
标准SQL
create procedure aver_score(course_name varchar(10))
as
begin
select avg(Grade) from SC where Cno=
(select Cno from Course where Cname=course_name);
end
或者
create procedure AVG_Cscore(course_name char(10))
as
select avg(Grade)
from SC,Course
where SC.Cno=Course.Cno and Course.Cname=course_name
T-SQL
--建表
create table Avg_Grade
(
Cname char(10), --课程名称
Cno int, --课程号
A_Gra int --该课程的平均成绩
);
--存储过程
if (exists(select * from sys.objects where name='Course_AVG'))
drop procedure Course_AVG
go
create procedure Course_AVG
@Cname char(10)
as
begin transaction trans
declare --定义变量
@Cno char(20), --课程号
@Cavg int --平均成绩
begin
select Cno=@Cno from Course where Cname=@Cname;
if @Cno is null
begin
print'+@Cname+不存在'
rollback; --回滚事务
return;
end;
end;
--select @Cavg=avg(Grade) from SC where Cno =@Cno;
--update Avg_Grade set A_Gra=@Cavg where Cno =@Cno and Cname =@Cname;
select @Cavg=avg(Grade) from SC where Cno=@Cno;
print @Cname+'平均分:'+convert(varchar,@Cavg);
commit;
return;
--执行存储
EXEC Course_AVG
@Cname='数据库';
create procedure aver_score
@course_name varchar(10)
as
select avg(Grade) from SC where Cno=
(select Cno from Course where Cname=@course_name);
或者
create procedure AVG_Cscore
@course_name char(10)
as
select avg(Grade)
from SC,Course
where SC.Cno=Course.Cno and Course.Cname=@course_name;
（3）将学生选课成绩从百分制改为等级制 (即A、 B、C、D、E)
标准SQL和T-SQL一样
--存储过程
alter table SC add level char(1) --增加level存储等级
if (exists (select * from sys.objects where name = 'get_Level'))
drop procedure get_level
go
create procedure get_level
as
update SC set level='A' where Grade>=90 and Grade<=100;
update SC set level='B' where Grade>=80 and Grade<90;
update SC set level='C' where Grade>=70 and Grade<80;
update SC set level='D' where Grade>=60 and Grade<70;
update SC set level='E' where Grade<60;
----执行过程
EXEC get_Level
select * from SC;
