TypeError: list indices must be integers, not str - Python - MySQL

I need your help because i dont know why i get this error when i try to update a register on my MySQL database. I have a GUI that i did with Python´s Tkinter, i able to create, delete and see the data in my DB but when i tried to apply an update i got the following error. What i want to do is that the user is able to say in what field he wants to do the update, what value he wants to update and finally the criteria in the WHERE statement.

Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Python27\lib\lib-tk\Tkinter.py", line 1541, in __call__
return self.func(*args)
File "C:\Users\efrias002\Desktop\Python\SQL Tkinter v2.py", line 136, in 
cambiar
cursor.execute("UPDATE base17 SET %s='Erick' WHERE ID =%s",[d2][d1])
TypeError: list indices must be integers, not str

I am using Python 2.7 and my code is this:

def win2 ():
  t1 = Toplevel(bg="Brown")
  t1.title("Modificar Datos")
  t1.geometry('580x400')
  t1.focus_set()
  t1.grab_set()
  t1.transient(master=ventana)
  t1.resizable(width = FALSE, height = FALSE)


  lb1 = Label(t1,text='ID del Registro',bg="Cyan2")
  lb1.grid(row=5, column=1,padx=70,pady=10)

  inf2=StringVar()
  t2=Entry(t1,textvariable=inf2)
  t2.grid(row=6,column=1,pady=15)

  lb2 = Label(t1,text='Campo del Dato a Modificar',bg="Cyan2")
  lb2.grid(row=5, column=3,padx=25,pady=5)

  inf3=StringVar()
  t3=Entry(t1,textvariable=inf3)
  t3.grid(row=6,column=3,pady=15)

  lb3 = Label(t1,text='Dato a Modificar',bg="Cyan2")
  lb3.grid(row=11, column=2,padx=10,pady=10)

  inf4=StringVar()
  t4=Entry(t1,textvariable=inf4)
  t4.grid(row=12,column=2,pady=10)

  def cambiar():
         d1= inf2.get()
         d2= inf3.get()
         d3= inf4.get()
         conn = MySQLdb.connect(host = "127.0.0.1", user = "root", passwd = "unitec", db = "efrias002")
         cursor = conn.cursor()
         cursor.execute("UPDATE base17 SET %s='Erick' WHERE ID =%s",[d2][d1])
         conn.commit()
         conn.close()

         tkMessageBox.showinfo("Info","Registro Modificado")



  wb = Frame(t1, width = 15, height = 10)
  b1 = Button(wb, text = "Cerrar(X)", bg = "SkyBlue", command = t1.destroy)
  b1.pack()
  wb.grid(column = 1, row = 13, pady=85)

  wc = Frame(t1, width = 15, height = 10)
  b2 = Button(wc, text = "Enviar", bg = "Orange", command = cambiar)
  b2.pack()
  wc.grid(column = 2, row = 13, pady=35)