Tkinter - Trace.() not working with variables

Question

I'm trying to set here two fields which interact with each other. In this case, what I'm looking for is to use the variable "code", which will be written within the code_entry and then, I will use this code to bring the description from a sql database. The problem is that it doesn't do anything when I write any number, what's the issue?

    def frame_basic_info_widgets():
        pm_master_var   = tk.StringVar(frame_basic_info,"0")
        size            = tk.StringVar(frame_basic_info,"")
        series          = tk.StringVar(frame_basic_info,"")
        colour          = tk.StringVar(frame_basic_info,"")
        code            = tk.IntVar(frame_basic_info,0)
        global product_description
        product_description = tk.StringVar(frame_basic_info,"No Product Selected")
        n               = 0
        product_master_fields = {"Size"   :"Product Size",
                                 "Series" :"Product Series",
                                 "Colour" :"Product Colour"}

        code_entry = tk.Entry(frame_basic_info,textvariable = code,bg="light grey").grid(row=0,column=0,pady=20,padx=20)
        product_label = tk.Label(frame_basic_info,textvariable = product_description,bg="light grey").grid(row=0,column=1,pady=20,padx=20)

        def change_product_description():
            print(code.get())
            product_description = pd.read_sql_query('SELECT product_description FROM Product_Master WHERE id = '+code.get(), engine)
            product_label.update()
            print(product_description)

        product_description.trace("w",change_product_description)

'''