ORA-00904: invalid identifier PL/SQL - oracle-sqldeveloper

Question

I am new to PL/SQL and I can't figure out what is the problem in the following function, as I get the error ORA-00904: par_cantitate invalid identifier. Please, please could you help me. Thank you!
CREATE OR REPLACE FUNCTION vanzari_med(par_cantitate
ProduseVandute.Cantitate%TYPE)
RETURN NUMBER IS
c ProduseVandute.Cantitate%TYPE;
s Medicament.Stoc%TYPE;
NO_SALES EXCEPTION;
BEGIN
SELECT Stoc INTO s
FROM ProduseVandute pv, Medicament m
WHERE pv.Cantitate=m.Stoc and Cantitate=par_cantitate;
IF s<>15
THEN RAISE NO_SALES;
ELSE
SELECT Cantitate INTO c
FROM ProduseVandute pv, Medicament m,(SELECT * FROM Vanzari GROUP
BY ID_Vanzari)v
WHERE Cantitate=par_cantitate and pv.Cantitate=m.Stoc and
pv.ID_Vanzari=v.ID_Vanzari;
END IF;
RETURN c;
END vanzari_med

Answer 1

Are you sure? If tables you used contain at least columns from this function, then it compiles. Though, as you didn't handle exception you raised, it might not work properly, but - it compiles.
Sample tables:
SQL> CREATE TABLE ProduseVandute
2 (
3 cantitate NUMBER,
4 id_vanzari NUMBER
5 );
Table created.
SQL> CREATE TABLE medicament
2 (
3 stoc NUMBER
4 );
Table created.
SQL> CREATE TABLE vanzari
2 (
3 id_vanzari NUMBER
4 );
Table created.
Your function, unmodified (just added terminators at the end):
SQL> CREATE OR REPLACE FUNCTION vanzari_med(par_cantitate
2 ProduseVandute.Cantitate%TYPE)
3 RETURN NUMBER IS
4 c ProduseVandute.Cantitate%TYPE;
5 s Medicament.Stoc%TYPE;
6 NO_SALES EXCEPTION;
7 BEGIN
8 SELECT Stoc INTO s
9 FROM ProduseVandute pv, Medicament m
10 WHERE pv.Cantitate=m.Stoc and Cantitate=par_cantitate;
11 IF s<>15
12 THEN RAISE NO_SALES;
13 ELSE
14 SELECT Cantitate INTO c
15 FROM ProduseVandute pv, Medicament m,(SELECT * FROM Vanzari GROUP
16 BY ID_Vanzari)v
17 WHERE Cantitate=par_cantitate and pv.Cantitate=m.Stoc and
18 pv.ID_Vanzari=v.ID_Vanzari;
19 END IF;
20 RETURN c;
21 END vanzari_med;
22 /
Function created.
SQL>