Make A Dynamic Cursor In A Stored Procedure

I need im my aplication to meke a "Cursor" in a execution of a stored procedure.

For sample:

In a table with a report definition I have the "Fileds, From, Group, Order " clausulas and I need make a cursor with a contents of this fileds.

How can I do ???

My code:

Declare @idRelat int, @cmd_FROM nvarchar(1024), @cmd_Det nvarchar(50)
SELECT @idRelat = idRelat, @cmd_Det = cmd_DET
FROM Relatórios WHERE Nome = @p_Relat

Declare @Tot_Col smallint, @Tot_Lin smallint, @Campos smallint,
@Aux_Select nvarchar(1024), @Aux_Group nvarchar(1024), @Aux_Order nvarchar(1024)

Select @Tot_Col = 0
Select @Tot_Lin = 0
Select @Campos = 0
Select @Aux_Select = "SELECT " + @cmd_DET + "AS Soma"
Select @Aux_Group = "GROUP BY "
Select @Aux_Order = "ORDER BY "
Declare @a_Local char(1), @a_Linha smallint, @a_Campo nvarchar(50)
Declare cur_Aux insensitive cursor for
SELECT Local, Linha, Campo
From Relatórios_Margens
WHERE (idRelat = @idRelat)
ORDER BY Local, Linha
Open cur_Aux
Fetch cur_Aux into @a_Local, @a_Linha, @a_Campo
While @@FETCH_status = 0 begin
If @a_Local = "C"
Select @Tot_Col = @Tot_Col + 1
Else
Select @Tot_Lin = @Tot_Lin + 1
Select @Campos = @Campos + 1
If @Aux_Group <> "GROUP BY " begin
Select @Aux_Group = @Aux_Group + ", "
If @Aux_Order <> "ORDER BY " begin
Select @Aux_Order = @Aux_Order + ", "
Select @Aux_Select = sSelect + ", " + @a_Campo + " AS Campo" + @Campos
Select @Aux_Group = @Aux_Group + @a_Campo
Select @Aux_Order = @Aux_Order + @a_Campo
Fetch cur_Aux into @a_Local, @a_Linha, @a_Campo
End
Select @Aux_Select = @Aux_Select
-- <<<< MONTA COMANDO SQL
Select @Aux_Select = @Aux_Select + " " + @cmd_FROM + " " + @p_Filtro + " " + @Aux_Group + " " + @Aux_Order
Declare @Cursor_Aux cursor
Set @Cursor_Aux = cursor for @Aux_Select
Open @Cursor_Aux

Not working !!!!