Oracle Sql Function Compiled (with errors) - oracle

Question

i am using below function to change the password ,
it give me compilation error once i compile
CREATE or replace FUNCTION updatePassword(CurrentP VARCHAR2,NewPwd VARCHAR2,StudentId VARCHAR2) RETURN VARCHAR2
is
getCount integer :=0;
BEGIN
Select count(*) into getCount from users where student_id=StudentId and Password=md5(CurrentP);
if getCount == 1
then
update users set Password=md5(NewPwd) where student_id=StudentId and Password=md5(CurrentP);
else
getCount = 0
RETURN getCount;
END;
/
i want to return getCount value on successfully update password else it return 0
below is error mention
UPDATEPASSWORD Compiled (with errors)

Answer 1

You have some PL/SQL syntax issues
CREATE or replace FUNCTION updatePassword(CurrentP VARCHAR2,NewPwd VARCHAR2,StudentId VARCHAR2) RETURN VARCHAR2
is
getCount integer :=0;
BEGIN
Select count(*) into getCount from users where student_id=StudentId and Password=md5(CurrentP);
if getCount = 1
then
update users set Password=md5(NewPwd) where student_id=StudentId and Password=md5(CurrentP);
else
getCount := 0;
end if;
RETURN getCount;
END;
/

Answer 2

You have a little syntax error. The code should look likes this:
CREATE or replace FUNCTION updatePassword(
CurrentP in VARCHAR2,
NewPwd in VARCHAR2,
StudentId in number) RETURN number
is
getCount number:=0;
BEGIN
Select count(*) into getCount from users where student_id=StudentId and Password=md5(CurrentP);
if getCount = 1
then
update users set Password=md5(NewPwd) where student_id=StudentId and Password=md5(CurrentP);
end if;
RETURN getCount;
END;
UPDATE:
After a closer look, you have a lot of syntax problems^^ Modified the code.
Suggestions:
Avoid stand alone functions/procedures. Use the Oracle advantage - packages. Helps to avoid invalidated objects situation;
When you use PL/SQL - try to stick with the coding standards in PL/SQL.
Set the correct types of variables.

Answer 3

Here's an example which shows how to do that.
First, test case. The MD5 function doesn't do anything; it just returns the IN parameter's value.
SQL> CREATE TABLE users
2 (
3 student_id VARCHAR2 (10),
4 password VARCHAR2 (20)
5 );
Table created.
SQL> INSERT INTO users (student_id, password)
2 VALUES ('100', 'Stack');
1 row created.
SQL> CREATE OR REPLACE FUNCTION md5 (par_password IN VARCHAR2)
2 RETURN VARCHAR2
3 IS
4 BEGIN
5 RETURN par_password;
6 END;
7 /
Function created.
SQL>
You should use a procedure to modify a password, not a function as you can't perform DML in a function (OK, you can, but you shouldn't. I'll show you show to do that later).
The procedure returns number of updated rows; if you want, you can return getcount (which is number of selected rows).
SQL> CREATE OR REPLACE PROCEDURE updatepassword (p_currentp IN VARCHAR2,
2 p_newpwd IN VARCHAR2,
3 p_studentid IN VARCHAR2,
4 retval OUT NUMBER)
5 IS
6 getcount INTEGER := 0;
7 BEGIN
8 SELECT COUNT (*)
9 INTO getcount
10 FROM users
11 WHERE student_id = p_studentid
12 AND password = md5 (p_currentp);
13
14 IF getcount = 1
15 THEN
16 UPDATE users
17 SET password = md5 (p_newpwd)
18 WHERE student_id = p_studentid
19 AND password = md5 (p_currentp);
20
21 retval := SQL%ROWCOUNT;
22 END IF;
23 END;
24 /
Procedure created.
SQL>
Testing: change password from "Stack" to "Overflow":
SQL> SET SERVEROUTPUT ON;
SQL>
SQL> DECLARE
2 l_retval NUMBER;
3 BEGIN
4 updatepassword ('Stack',
5 'Overflow',
6 '100',
7 l_retval);
8 DBMS_OUTPUT.put_line ('retval = ' || l_retval);
9 END;
10 /
retval = 1
PL/SQL procedure successfully completed.
SQL> SELECT * FROM users;
STUDENT_ID PASSWORD
---------- --------------------
100 Overflow
SQL>
Seems to be OK.
And here's why you can't use a function:
SQL> DROP PROCEDURE updatepassword;
Procedure dropped.
SQL> CREATE OR REPLACE FUNCTION updatepassword (p_currentp IN VARCHAR2,
2 p_newpwd IN VARCHAR2,
3 p_studentid IN VARCHAR2)
4 RETURN NUMBER
5 IS
6 getcount INTEGER := 0;
7 BEGIN
8 SELECT COUNT (*)
9 INTO getcount
10 FROM users
11 WHERE student_id = p_studentid
12 AND password = md5 (p_currentp);
13
14 IF getcount = 1
15 THEN
16 UPDATE users
17 SET password = md5 (p_newpwd)
18 WHERE student_id = p_studentid
19 AND password = md5 (p_currentp);
20 END IF;
21
22 RETURN getcount;
23 END;
24 /
Function created.
SQL> SELECT updatepassword ('Overflow', 'Littlefoot', '100') FROM DUAL;
SELECT updatepassword ('Overflow', 'Littlefoot', '100') FROM DUAL
*
ERROR at line 1:
ORA-14551: cannot perform a DML operation inside a query
ORA-06512: at "SCOTT.UPDATEPASSWORD", line 16
SQL>
Finally, a function which shows that you can do DML (but you really don't want to do that) - use pragma autonomous_transaction which instructs Oracle to execute code within that function separately from an outside transaction. It requires you to commit (or rollback).
SQL> CREATE OR REPLACE FUNCTION updatepassword (p_currentp IN VARCHAR2,
2 p_newpwd IN VARCHAR2,
3 p_studentid IN VARCHAR2)
4 RETURN NUMBER
5 IS
6 PRAGMA AUTONOMOUS_TRANSACTION;
7 getcount INTEGER := 0;
8 BEGIN
9 SELECT COUNT (*)
10 INTO getcount
11 FROM users
12 WHERE student_id = p_studentid
13 AND password = md5 (p_currentp);
14
15 IF getcount = 1
16 THEN
17 UPDATE users
18 SET password = md5 (p_newpwd)
19 WHERE student_id = p_studentid
20 AND password = md5 (p_currentp);
21 END IF;
22
23 COMMIT;
24
25 RETURN getcount;
26 END;
27 /
Function created.
SQL> SELECT updatepassword ('Overflow', 'Littlefoot', '100') FROM DUAL;
UPDATEPASSWORD('OVERFLOW','LITTLEFOOT','100')
---------------------------------------------
1
SQL> select * from users;
STUDENT_ID PASSWORD
---------- --------------------
100 Littlefoot
SQL>