Gui program to connect database and store data

Database Connectivity

import mysql.connector as sql
from tkinter import *
from tkinter import messagebox
db=sql.connect(host='localhost',
                           user='root',
                           password='',
                           database='school'
                           )
my_cur=db.cursor()
root=Tk()
root.geometry("250x300")
Label(root,text="Student Details",font="arial 14 bold").grid(row=0,column=1,columnspan=3)
Label(root,text="").grid(row=1,column=0)
Label(root,text="Roll Number ").grid(row=2,column=0)
Label(root,text="").grid(row=3,column=0)
Label(root,text="Name ").grid(row=4,column=0)
Label(root,text="").grid(row=5,column=0)
Label(root,text="Gender ").grid(row=6,column=0)
Label(root,text="").grid(row=7,column=0)
Label(root,text="City ").grid(row=8,column=0)
Label(root,text="").grid(row=9,column=0)
roll=StringVar()
name=StringVar()
gender=StringVar()
city=StringVar()
e1=Entry(root,textvariable=roll).grid(row=2,column=1,columnspan=2)
e2=Entry(root,textvariable=name).grid(row=4,column=1,columnspan=2)
r1=Radiobutton(root,text="Male",value='M',textvariable=gender).grid(row=6,column=1)
r2=Radiobutton(root,text="Female",value='F',textvariable=gender).grid(row=6,column=2)
e3=Entry(root,textvariable=city).grid(row=8,column=1,columnspan=2)

def save_data():
    r=roll.get()
    n=name.get()
    g=gender.get()
    print(g)
    c=city.get()
    my_cur.execute("insert into student(roll,name,gender,city)values('{}','{}','{}','{}')".format(r,n,g,c))
Button(root,text="Save",command=save_data).grid(row=10,column=1)
root.mainloop()