存储过程例子（1）

/*

用PLSQL语言编写一个程序。按系(系名）分段统计（成绩小于60分，60-85分, 85分以上）

“大学物理”课程各分数段的学生人数，及各系学生的平均成绩。

可能的SQL：

系: select dno,dname from dep;

成绩：select grade from sc where cno = (select cno from course where cname=???)

and sno in (select sno from student where dno=???);

平均成绩：select avg(grade) from sc where cno = (select cno from course where cname=???)

and sno in (select sno from student where dno=???);

*/

set serveroutput on

declare

–系

cursor cdep is select dno,dname from dep;

pdno dep.dno%type;

pdname dep.dname%type;

–成绩

cursor cgrade(depNo number,courseName varchar2)

is select grade from sc where cno = (select cno from course where cname=courseName)

and sno in (select sno from student where dno=depNo);

pgrade sc.grade%type;

–计数器

count1 number; count2 number;count3 number;

–平均分

avgGrade number;

–课程名称

pcourseName varchar2(40) := ‘大学物理’;

begin

open cdep;

loop

–取一个系

fetch cdep into pdno,pdname;

exit when cdep%notfound;

--计数器
count1:=0;count2:=0;count3:=0;
--平均成绩：
select avg(grade) into avggrade from sc
where cno = (select cno from course where cname=pcourseName)
and sno in (select sno from student where dno=pdno);
--得到该系学生的成绩
open cgrade(pdno,pcourseName);
loop
--取一个学生的成绩
fetch cgrade into pgrade;
exit when cgrade%notfound;

--判断
if pgrade<60 then count1:=count1+1;
elsif pgrade>=60 and pgrade<85 then count2:=count2+1;
else count3:=count3+1;
end if;

end loop;
close cgrade;

--保存当前系
insert into msg values(pcourseName,pdname,count1,count2,count3,avggrade);

end loop;

close cdep;

commit;

dbms_output.put_line(‘完成’);

end;

/