What is the correct way to use nested functions in PLSQL?

Question

I want to know the correct way to use nested functions in PLSQL. In the following snippet the function 'to_number' works fine, but my two nested functions can't be used in the same manner.

Declare
  Tettt Number;
  Function lolazo(pigt Number, p_Fecha_Fact Date)
  Return Number Is
    resultado number;
  Begin
    Select Vp.Valor
    into resultado
    from valor_precio vp
    Where Vp.Id_Tipo_Cargo = 103
      And Vp.Id_Grupo_Precio = pigt
      and vp.f_inicio_precio =
        (select max(vp2.f_inicio_precio)
         From Valor_Precio Vp2
         Where Vp2.Id_Grupo_Precio = pigt
           And Vp2.F_Inicio_Precio < p_fecha_fact
           And Vp2.Id_Tipo_Cargo = 103 );
    Return Resultado;
  End Lolazo;
  Function Multi(Uno Number, Dos Number) Return Number Is
  Begin
    return uno*dos;
  End Multi;
Begin
  Select to_number('123')
  Into Tettt
  From Dual;

--  Doesn't work!
--  Select lolazo(1544, to_date('01/01/2011','dd/mm/yyyy')) 
--  Into Tettt
--  From Dual;

--  Doesn't work!
--  select Multi(2,3) into Tettt from dual;

Dbms_Output.Put_Line(lolazo(1544, to_date('01/01/2011','dd/mm/yyyy')));
Dbms_Output.Put_Line(Multi(2,3));
dbms_output.put_line(Tettt);
end;

Answer 1

Your functions can't be used in SQL, so DO NOT: select into some_variable from dual.

Try using an assignment:

Tettt := Multi(2,3);

Also, post your errors from your script (instead of saying doesn't work). Much easier for us to see the actual issue.

If you really wanted to use these functions from SQL, you'd have to expose them to the SQL engine (outside of the PL/SQL world in which your anonymous block resides). This would typically involve creating separate stored procedures or defining them in some package specification.

Hope that helps.