Need an alternative solution to this oracle query?Without using (flag) variable - oracle

Question

Question:
Create a Doctor table (Docname, Qualification, Specialization, Working_shift).
Use parameterized cursor to check the availability of doctors given the specialization
and working shift of the day to serve the patients
I am just learning databases so if the question may seem trivial i apologize for that.
Getting the desired output on inputting the values but i need an alternative way to solve the question without using flag variable (so that i could get the exception)...if i don't use the flag it prints the exception as well as the docname and qualification
I am using oracle(cursor in a normal pl/sql block) to execute this query.
Solution:
--table creation
create table doctor
(
docname varchar2(20),
qualification varchar2(20),
specialization varchar2(20),
shift varchar2(20)
)
my solution
declare
cursor c1 (specialization varchar2,shift varchar2) is select docname,qualification from doctor
where specialization='&sp' and shift='&shift'
sp doctor.specialization%type;
shift doctor.shift%type;
flag number(10);
begin
flag:=0;
for r1 in c1(sp,shift)
loop
if c1%found then
flag:=1;
dbms_output.put_line('Doctor is available');
dbms_output.put_line('Docname: '||r1.docname);
dbms_output.put_line('qualification: '||r1.qualification);
else
flag:=0;
end if;
end loop;
if flag=0 then
dbms_output.put_line('Invalid specialization/shift');
end if;
end;

Answer 1

Try given below code
declare
cursor c1 (specialization varchar2,shift varchar2)
is
select docname,qualification
from doctor
where specialization='&sp'
and shift='&shift'
sp doctor.specialization%type;
shift doctor.shift%type;
flag number(10);
begin
flag:=0;
for r1 in c1(sp,shift)
loop
if c1%found then
flag:=1;
dbms_output.put_line('Doctor is available');
dbms_output.put_line('Docname: '||r1.docname);
dbms_output.put_line('qualification: '||r1.qualification);
else
raise;
end if;
end loop;
exception
when others then
dbms_output.put_line('Invalid specialization/shift');
end;

Answer 2

You don't need to reset the flag within the loop, you already initialised it to 0 at the start of the procedure.
You dont need to check c1%found because you're inside the loop; by definition a record was found, otherwise it wouldn't go into your loop code.
Your cursor should use the variables provided, not the SQL*Plus substitution variables, e.g.:
cursor c1 (specialization varchar2,shift varchar2) is
select docname,qualification
from doctor
where doctor.specialization=c1.specialization
and doctor.shift=c1.shift;
If you don't want to have to use all those aliases, you can use a naming convention to distinguish between the different identifiers (shift vs shift), e.g.:
cursor c1 (i_specialization varchar2, i_shift varchar2) is
select docname,qualification
from doctor
where specialization=i_specialization
and shift=i_shift;
Note also, you missed a semicolon at the end of the query.
Finally:
If you change your loop as follows, it should work fine:
for r1 in c1(&sp,&shift)
loop
flag:=1;
dbms_output.put_line('Doctor is available');
dbms_output.put_line('Docname: '||r1.docname);
dbms_output.put_line('qualification: '||r1.qualification);
end loop;
Now, your last bit of code:
if flag=0 then
dbms_output.put_line('Invalid specialization/shift');
end if;
will work fine - it will only execute if flag is still 0 (i.e. the query found no rows).

Answer 3

If you do not use parameters in "c1" cursor you do not need it...
DECLARE
CURSOR c1 IS
SELECT docname, qualification
FROM doctor
WHERE specialization = '&sp'
AND shift = '&shift';
TYPE c1_ntt IS TABLE OF c1%ROWTYPE;
l_c1 c1_ntt;
BEGIN
OPEN c1;
FETCH c1 BULK COLLECT INTO l_c1;
CLOSE c1;
IF l_c1.COUNT = 0 THEN
RAISE_APPLICATION_ERROR(-20000, 'Invalid specialization/shift');
END IF;
FOR indx IN l_c1.FIRST..l_c1.LAST LOOP
DBMS_OUTPUT.PUT_LINE('Doctor is available');
DBMS_OUTPUT.PUT_LINE('Docname: ' || l_c1(indx).docname);
DBMS_OUTPUT.PUT_LINE('qualification: ' || l_c1(indx).qualification);
END LOOP;
END;