Question

Please help me out from this situation

I have to create a function to retrieve the name of the manager for a given employee. (I was trying to join the emp table to itself to do this but not sure.) Also I need to write
a SQL select statement that uses the function to produce a list of employee numbers and names together with the name of their manager

Thanks

Answer 1

Filip’s function is not the best solution for a function which is called from a query of the EMP table. That table has the MGR attribute and that is what should be passed to the function.

CREATE FUNCTION fn_get_manager(p_mgr IN emp.mgr%type) 
   RETURN VARCHAR2
IS 
   manager emp.ename%type;
BEGIN 
   SELECT ename 
     INTO manager 
     FROM emp e 
    WHERE e.empno = p_mgr; 
   RETURN(manager); 
END;

These things perform badly enough without introducing another unnecessary read on the EMP table.

But as Filip days, this properly should be done in SQL, with a JOIN of the EMP table to itself.