SQL Oracle - Procedure Syntax (School assignment) - sql

Question

I'm currently learning SQL and I'm having trouble with a procedure of mine. The procedure should calculate the average of a column called 'INDICE_METABO_PAT'. The information I need is in 3-4 different tables. Then when I do have the average calculated, I update a table to set this average to the corresponding entries. Here is the procedure. Note that everything else in my .sql file works : inserts, updates, selects, views, etc.
create or replace Procedure SP_UPDATE_INDICE_METABO_DV (P_NO_ETUDE in number)
is
V_SOMME number := 0;
V_NBPATIENT number := 0;
V_NO_ETUDE number := P_NO_ETUDE;
cursor curseur is
select PATIENT.INDICE_EFFICACITE_METABO_PAT
from ETUDE, DROGUE_VARIANT, ETUDE_PATIENT, PATIENT
where ETUDE.NO_DROGUE = DROGUE_VARIANT.NO_DROGUE
and ETUDE.NO_VAR_GEN = DROGUE_VARIANT.NO_VAR_GEN
and V_NO_ETUDE = ETUDE_PATIENT.NO_ETUDE
and ETUDE_PATIENT.NO_PATIENT = PATIENT.NO_PATIENT;
begin
open curseur;
fetch curseur into V_SOMME;
V_NBPATIENT := V_NBPATIENT + 1;
exit when curseur%NOTFOUND;
update DROGUE_VARIANT
set INDICE_EFFICACITE_METABO_DV = V_SOMME / V_NBPATIENT
where exists(select * from ETUDE, DROGUE_VARIANT, ETUDE_PATIENT, PATIENT
where ETUDE.NO_DROGUE = DROGUE_VARIANT.NO_DROGUE
and ETUDE.NO_VAR_GEN = DROGUE_VARIANT.NO_VAR_GEN
and V_NO_ETUDE = ETUDE_PATIENT.NO_ETUDE
and ETUDE_PATIENT.NO_PATIENT = PATIENT.NO_PATIENT);
end SP_UPDATE_INDICE_METABO_DV;
/
I'm getting an error : Procedure compiled , error check compiler log.
But I can't open the compiler log, and when my friend opens it, it points to weird places, like my create tables and such.
This is school stuff by the way, so it'll be nice if you could give an insight instead of a direct solution. Thanks alot.
Thanks alot in advance for your kind help !

Answer 1

To see the error you can do show errors after your procedure creation statement, or you can query the user_errors or all_errors views.
That will show something like:
LINE/COL ERROR
-------- ------------------------------------------------------------------------
20/4 PLS-00376: illegal EXIT/CONTINUE statement; it must appear inside a loop
20/4 PL/SQL: Statement ignored
You mentioned that when you checked the complier log, which shows the same information, "it points to weird places". Presumably you're looking at line 20 in your script. But this message is referring to line 20 of the PL/SQL code block, which is the exit when curseur%NOTFOUND;, which makes sense for the error message.
And as the message also says, and as #ammoQ said in a comment, that should be in a loop. If you're trying to manually calculate the average in a procedure as an exercise, instead of using the built-in aggregation functions, then you need to loop over all of the rows from your cursor:
open curseur;
loop
fetch curseur into V_SOMME;
exit when curseur%NOTFOUND;
V_NBPATIENT := V_NBPATIENT + 1;
end loop;
close curseur;
But as you'll quickly realise, you'll end up with the v_somme variable having the last value retrieved, not the sum of all the values. You need a separate variable keep to track of the sum - fetch each value into a variable, and add that to your running total, all within the loop. But as requested, not giving a complete solution.
As you're starting out you should really use ANSI join syntax, not the old from/where syntax you have now. It's a shame that is still being taught. So your cursor query should be something like:
select PATIENT.INDICE_EFFICACITE_METABO_PAT
from ETUDE_PATIENT
join ETUDE
-- missing on clause !
join DROGUE_VARIANT
on DROGUE_VARIANT.NO_DROGUE = ETUDE.NO_DROGUE
and DROGUE_VARIANT.NO_VAR_GEN = ETUDE.NO_VAR_GEN
join PATIENT
on PATIENT.NO_PATIENT = ETUDE_PATIENT.NO_PATIENT
where ETUDE_PATIENT.NO_ETUDE = P_NO_ETUDE;
... which shows you that you are missing a join condition between ETUDE_PATIENT and ETUDE - it's unlikely you want a cartesian product, and it's much easier to spot that missing join using this syntax than with what you had.
You need to look at your update statement carefully too, particularly the exists clause. That will basically always return true if the cursor found anything, so it will update every row in DROGUE_VARIANT with your calculated average, which presumably isn't what you want.
There is no correlation between the rows in the table you're updating and the subquery in that clause - the DROGUE_VARIANT in the subquery is independent of the DROGUE_VARIANT you're updating. By which I mean, it's the same table, obviously; but the update and the subquery are looking at the table separately and so are looking at different rows. It also has the same missing join condition as the cursor query.