Debugging PL/SQL Procedure for reservation service report - oracle

Question

For a school project, unable to figure out how to debug the code, I've managed to figure out that the problem is in this line of code: Reservation_id:=: reservation_ID; but I am unsure how to fix it
Set serveroutput ON;
Create or replace procedure Reservation_Services_Report (reservation_ID IN number)
As
Service_number reservation.service_type_id%type;
People_attending reservation.numb_people_attend%type;
Begin
Reservation_id:=: reservation_ID;
Select s.service_name, s.service_type, s.service_type_food, s.service_type_entertainment, r.numb_people_attend from services s, reservation r
where services.service_type_id = reservation.service_type_id;
Exception
When no_data_found then
dbm_output.put_line(‘No services for this reservation’);
End;

Answer 1

Oh, it only it were your only problem!
as you declared an IN parameter, why don't you use it? It is here to be passed to the procedure, not to accept it at runtime (which is what you planned to do with preceding its name with a colon).
besides, it is a good idea to distinguish parameter name from column name, otherwise you'll have problems as Oracle won't know which is which. That's why I renamed it to par_reservation_id
select in PL/SQL requires into clause. In your case, you need to declare all those variables which match select column list. I named them all with the l_ prefix (as a l_ocal variable); some people use v_; pick whichever you want, just try to stick to some standards - it'll make your code easier to read, debug and maintain
select you wrote would probably return too_many_rows error as there's no restriction to number of rows; I presume you "forgot" to include the where clause so I put it there; I don't know whether it is correct or not as I don't have your tables. Fix it, if necessary
when joining tables, try to switch to modern ANSI syntax and separate joins from (where) conditions, as I tried
unless you're running that code in a tool that supports dbms_output to be displayed on the screen, you won't see anything. Exception is handled (kind of), but nobody will know what happened. Consider raising the error instead, e.g. raise_application_error(-20000, 'No services for this reservation')
Here's how the procedure might look like; hopefully, it is somewhat better than the original version. See if it helps.
Create or replace procedure
Reservation_Services_Report (par_reservation_ID IN number)
As
l_service_name services.service_name%type;
l_service_type services.service_type%type;
l_service_type_Food services.service_type_Food%type;
l_service_type_entertainment services.service_type_entertainment%type;
l_numb_people_attend reservation.numb_people_attend%type;
Begin
Select s.service_name,
s.service_type,
s.service_type_food,
s.service_type_entertainment,
r.numb_people_attend
into l_service_name,
l_service_type,
l_service_type_food,
l_service_type_entertainment,
l_numb_people_attend
from services s join reservation r on s.service_type_id = r.service_type_id
where r.reservation_id = par_reservation_id;
Exception
When no_data_found then
dbms_output.put_line(‘No services for this reservation’);
End;