I want to get a date from a Tk.entry

Question

I have tried to use many variables and adding datetime.date but it doesn't work, I will leave my code so that anybody can make it work. I tried to get the numbers from fetch and then used datetime.date but it says that I need to declare the year or something like that. I need that thing to be a date to put it in the SQL database.

    fecha = tk.Entry(vent1)
    fecha.place(x=80, y=5, width=170, height=30)
    fechaL = tk.Label(vent1, text="FECHA")
    fechaL.place(x=10, y=7)

    nombre=tk.Entry(vent1)
    nombre.place(x=80,y=40,width=170,height=30)
    nom=tk.Label(vent1,text="nombre")
    nom.place(x=10,y=45,)


    rubro=tk.Entry(vent1)
    rubro.place(x=80, y=80, width=170, height=30)
    rubroL = tk.Label(vent1,text='rubro')
    rubroL.place(x=10, y=86)

    precio=tk.Entry(vent1)
    precio.place(x=80, y=120, width=170, height=30)
    precioL=tk.Label(vent1,text="precio")
    precioL.place(x=10, y=126)

    # guardar funcion

    fechad=fecha.get()
    fechad = datetime.datetime(day,month,year)
    nombred = nombre.get()
    rubrod = rubro.get()
    preciod = precio.get()
    conn = sql3.connect('costos.db')

    cursor = conn.cursor()
  #  cursor.execute("""CREATE TABLE COSTOS(fecha integer,nombre text,rubro text,costo integer)""")
    def guardar():
        cursor.execute("INSERT INTO COSTOS VALUES(:fecha,:nombre,:rubro,:costo)",{"fecha":fechad, "nombre":nombred,"rubro":rubrod,"costo":preciod})
        cursor.execute("SELECT*FROM COSTOS WHERE fecha='25/7/2021'")
        print(cursor.fetchall())
        conn.commit()
        conn.close()




    save=tk.Button(vent1, text="guardar",command=guardar)
    save.place(x=260, y=69)





app.mainloop()