PLSql -- 练习2 cursor 显式/隐式游标

问题

解决1

分析

--Sql
select distinct sc.course_no from hand_student_core sc  ;
-- cursor cno -> exit when nofound
select sc.core from hand_student_core sc where sc.course_no='c001';
-- cursor core(no)  --> exit when  nofound
-- using variable
cnum1,cnum2,cnum3,cnum4
cno_tmp

declare
cnum1 number;
cnum2 number;
cnum3 number;
cnum4 number;
cursor cno is
select distinct sc.course_no from hand_student_core sc;
cursor sccore(cno_tmp hand_student_core.course_no%type) is
select sc.core from hand_student_core sc where sc.course_no = cno_tmp;
c_no    hand_student_core.course_no%type;
sc_core hand_student_core.core%type;

begin
dbms_output.put_line('course_no  [100-85]   [85-70]   [70-60]   [<60]');
open cno;
loop
fetch cno
into c_no;
exit when cno%Notfound;
cnum1 := 0;
cnum2 := 0;
cnum3 := 0;
cnum4 := 0;
open sccore(c_no);
loop
fetch sccore
into sc_core;
exit when sccore%NOTFOUND;

if sc_core >= 85 and sc_core < 100 then
cnum1 := cnum1 + 1;
elsif sc_core >= 70 and sc_core < 85 then
cnum2 := cnum2 + 1;
elsif sc_core >= 60 and sc_core < 75 then
cnum3 := cnum3 + 1;
else
cnum4 := cnum4 + 1;
end if;
end loop;
close sccore;
dbms_output.put_line('    ' || c_no || '             ' || cnum1 ||
'              ' || cnum2 || '            ' ||
cnum3 || '            ' || cnum4);
end loop;
close cno;
exception
when no_data_found then
dbms_output.put_line('no data found');
when others then
dbms_output.put_line('others');
end;

解决2

隐式游标

declare
cnum1 number;
cnum2 number;
cnum3 number;
cnum4 number;
c_no  hand_student_core.course_no%type;
begin
dbms_output.put_line('course_no  [100-85]   [85-70]   [70-60]   [<60]');

for result_cno in (select distinct course_no from hand_student_core) loop

cnum1 := 0;
cnum2 := 0;
cnum3 := 0;
cnum4 := 0;
c_no  := result_cno.course_no;

for result_core in (select sc.core
from hand_student_core sc
where sc.course_no = c_no) loop

if result_core.core >= 85 and result_core.core < 100 then
cnum1 := cnum1 + 1;
elsif result_core.core >= 70 and result_core.core < 85 then
cnum2 := cnum2 + 1;
elsif result_core.core >= 60 and result_core.core < 75 then
cnum3 := cnum3 + 1;
else
cnum4 := cnum4 + 1;
end if;
end loop;

dbms_output.put_line('    ' || c_no || '             ' || cnum1 ||
'              ' || cnum2 || '            ' ||
cnum3 || '            ' || cnum4);  end loop;

exception
when no_data_found then
dbms_output.put_line('no_data_found');
when others then
dbms_output.put_line('others');
end;

结果