How can this piece of PLSQL be made to compile? - oracle

Question

I need to return the names of employees in string format for all those employees whose manager ID depends on the passed parameter. When I compile the function I get an error. Here is the function code:
create or replace function Employee(v_manid IN employees.manager_id%type)
return varchar2
AS
cursor cur_emp is select last_name from employees where manager_id = v_manid;
v_names varchar2(10);
begin
for emp_rec in cur_emp
loop
v_name = v_name || emp_rec.last_name ||', ';
end loop;
return v_name
end;
/
The error is:
Error(8,8): PLS-00103: Encountered the symbol "=" when expecting one
of the following: := . ( # % ; Error(8,44): PLS-00103:
Encountered the symbol ";" when expecting one of the following: )
, * & - + / at mod remainder rem and or ||
Could anyone help me with this?

Answer 1

As stated in the other answers the reason why your function won't compile is threefold.
You've declared the variable v_names and are referencing it as v_name.
The assignment operator in PL/SQL is :=, you're using the equality operator =.
You're missing a semi-colon in your return statement; it should be return v_name;
It won't stop the function from compiling but the variable v_names is declared as a varchar2(10). It's highly unlikely that when a manager with multiple subordinates all their last names will fit into this. You should probably declare this variable with the maximum size; just in case.
I would like to add that you're doing this a highly inefficient way. If you were to do the string aggregation in SQL as opposed to a PL/SQL loop it would be better. From 11g release 2 you have the listagg() function; if you're using a version prior to that there are plenty of other string aggregation techniques to achieve the same result.
create or replace function employee ( p_manid in employees.manager_id%type
) return varchar2 is
v_names varchar2(32767); -- Maximum size, just in case
begin
select listagg(lastname, ', ') within group ( order by lastname )
into v_names
from employees
where manager_id = p_manid;
return v_names;
exception when no_data_found then
return null;
end;
/
Please note a few other changes I've made:
Prepend a different letter onto the function parameter than the variable to make it clear which is which.
Add in some exception handling to deal with there being no data for that particular manager.
You would have returned , if you had no data I return NULL. If you want to return a comma instead simply put this inside the exception.
Rather than bother to create a cursor and loop through it etc I let Oracle do the heavy lifting.
It's rather curious that you would want to return a comma delimited list as there is little that you would be able to do with it in Oracle afterwards. It might be more normal to return something like an array or an open cursor containing all the surnames. I assume, in this answer, that you have a good reason for doing what you are.

Answer 2

There are a couple of things to be noted.
Declared as v_names but used as v_name
Assignemnt should be like v_name := v_name || emp_rec.last_name ||
', ';
v_name is declared with size of 10, it would be too small and would
give an error when you execute, so you could declare as
v_name employees.last_name%TYPE;
You could create your function as
CREATE OR REPLACE FUNCTION employee (v_manid IN employees.manager_id%TYPE)
RETURN VARCHAR2
AS
v_name employees.last_name%TYPE;
CURSOR cur_emp
IS
SELECT last_name
FROM employees
WHERE manager_id = v_manid;
BEGIN
FOR emp_rec IN cur_emp
LOOP
v_name := v_name || emp_rec.last_name || ', ';
END LOOP;
RETURN v_name;
END;
/

Answer 3

I guess you should use := instead of =
like
v_name := v_name || emp_rec.last_name ||', ';
one more thing you also need to add semicolon ; at the end of return v_name like
return v_name;