Oracle Procedure with an IF-THEN-ELSE produces error - sql

Question

I have created this procedure in Oracle, to assign a role to a user based on the grade stored in the grade column of the marketing table. However, when I run it I get errors.
Initial Problem
CREATE OR REPLACE PROCEDURE proc_assign_role IS
vn_grade NUMBER(5);
CURSOR cur_user_grade IS
SELECT grade, username
FROM marketing
WHERE grade BETWEEN 1 AND 3;
BEGIN
FOR rec_cur_user_grade IN cur_user_grade
vn_grade:=
IF grade= 1
THEN
GRANT ROLE admin_staff;
ELSIF grade= 2 THEN
GRANT ROLE marketing_staff;
ELSIF grade= 3 THEN
GRANT ROLE event_staff;
END IF;
DBMS_OUTPUT.PUT_LINE(username||'YOU ARE A GRADE '||vn_grade|| 'USER');
END proc_assign_role;
/
This is the error I get:
ERROR at line 11: PLS-00103: Encountered the symbol "VN_GRADE" when expecting one of the following:
. ( * # % & - + / at loop mod remainder range rem ..
|| multiset
1. CREATE OR REPLACE PROCEDURE proc_assign_role IS
2. vn_grade NUMBER(5);

Answer 1

vn_grade:=
You need to assign a value to that line, or get rid of it. You can't assign an IF statement to a number variable. Probably get rid of it, then change your IF statement to look at the grade from the cursor. You also need to end your loop.
Additionally, you can't do a grant directly within a PL/SQL code block. You have to use the execute immediate statement for that. And you have to tell it who you're granting the role to.
FOR rec_cur_user_grade IN cur_user_grade LOOP
IF rec_cur_user_grade.grade= 1 THEN
execute immediate 'GRANT ROLE admin_staff to ' || rec_cur_user_grade.username;
ELSIF rec_cur_user_grade.grade= 2 THEN
execute immediate 'GRANT ROLE marketing_staff to ' || rec_cur_user_grade.username;
ELSIF rec_cur_user_grade.grade= 3 THEN
execute immediate 'GRANT ROLE event_staff to ' || rec_cur_user_grade.username;
END IF;
DBMS_OUTPUT.PUT_LINE(username||'YOU ARE A GRADE '||rec_cur_user_grade.grade|| 'USER');
END LOOP;

Answer 2

I'm seeing a few things that would keep this from working:
After your FOR statement, there's no LOOP statement (which is what the error is complaining about). There's also no END LOOP after your DBMS_OUTPUT.
vn_grade is followed by the := assignment operator, but nothing is being assigned to it.
The GRANT statements are written as bare DDL, which isn't allowed in PL/SQL. They need to be wrapped in EXECUTE IMMEDIATE.
grade and username need to be qualified by the cursor variable (e.g., rec_cur_user_grade.grade and rec_cur_user_grade.username).
Try something like this (which runs as an anonymous block, rather than a procedure, and uses an implicit cursor):
BEGIN
FOR rec_cur_user_grade IN (
SELECT grade, username
FROM marketing
WHERE grade BETWEEN 1 AND 3
)
LOOP
CASE rec_cur_user_grade.grade
WHEN 1 THEN
EXECUTE IMMEDIATE 'GRANT ROLE admin_staff TO ' || rec_cur_user_grade.username;
WHEN 2 THEN
EXECUTE IMMEDIATE 'GRANT ROLE marketing_staff TO ' || rec_cur_user_grade.username;
WHEN 3 THEN
EXECUTE IMMEDIATE 'GRANT ROLE event_staff TO ' || rec_cur_user_grade.username;
END CASE;
DMBS_OUTPUT.PUT_LINE(rec_cur_user_grade.username || ' YOU ARE A GRADE ' || rec_cur_user_grade.grade || ' USER');
END LOOP;
END;
/

Answer 3

grant is DDL and therefore cannot be used in PL/SQL directly. In order to accomplish this, the DDL needs to be executed dynamically, using execute immediately. Additionally, grant always requires you to specify the recipient of the role. The result would be something like this:
execute immediate 'GRANT ROLE admin_staff to ' || rec_cur_user_grade.username;
An ORA-00990: missing or invalid privilege error is fairly self-descriptive: the owner of the procedure does not have the necessary privileges to take the actions being attempted by the procedure.
The most likely culprit here is roles: permissions granted by a role cannot be used in a procedure. The first step you should take is to make sure that the owner of the procedure has been explicitly granted permission to administer the roles involved.