Here is the frontend.py in OOPstyle. The following code is also attachedin the resources as a Python file.

from tkinter import *
from backend import Database

database=Database("books.db")

class Window(object):

def __init__(self,window):

self.window = window

self.window.wm_title("BookStore")

l1=Label(window,text="Title")
l1.grid(row=0,column=0)

l2=Label(window,text="Author")
l2.grid(row=0,column=2)

l3=Label(window,text="Year")
l3.grid(row=1,column=0)

l4=Label(window,text="ISBN")
l4.grid(row=1,column=2)

self.title_text=StringVar()
self.e1=Entry(window,textvariable=self.title_text)
self.e1.grid(row=0,column=1)

self.author_text=StringVar()
self.e2=Entry(window,textvariable=self.author_text)
self.e2.grid(row=0,column=3)

self.year_text=StringVar()
self.e3=Entry(window,textvariable=self.year_text)
self.e3.grid(row=1,column=1)

self.isbn_text=StringVar()
self.e4=Entry(window,textvariable=self.isbn_text)
self.e4.grid(row=1,column=3)

self.list1=Listbox(window, height=6,width=35)
self.list1.grid(row=2,column=0,rowspan=6,columnspan=2)

sb1=Scrollbar(window)
sb1.grid(row=2,column=2,rowspan=6)

self.list1.configure(yscrollcommand=sb1.set)
sb1.configure(command=self.list1.yview)

self.list1.bind('<<ListboxSelect>>',self.get_selected_row)

b1=Button(window,text="View all", width=12,command=self.view_command)
b1.grid(row=2,column=3)

b2=Button(window,text="Search entry", width=12,command=self.search_command)
b2.grid(row=3,column=3)

b3=Button(window,text="Add entry", width=12,command=self.add_command)
b3.grid(row=4,column=3)

b4=Button(window,text="Update selected", width=12,command=self.update_command)
b4.grid(row=5,column=3)

b5=Button(window,text="Delete selected", width=12,command=self.delete_command)
b5.grid(row=6,column=3)

b6=Button(window,text="Close", width=12,command=window.destroy)
b6.grid(row=7,column=3)

def get_selected_row(self,event):
index=self.list1.curselection()[0]
self.selected_tuple=self.list1.get(index)
self.e1.delete(0,END)
self.e1.insert(END,self.selected_tuple[1])
self.e2.delete(0,END)
self.e2.insert(END,self.selected_tuple[2])
self.e3.delete(0,END)
self.e3.insert(END,self.selected_tuple[3])
self.e4.delete(0,END)
self.e4.insert(END,self.selected_tuple[4])

def view_command(self):
self.list1.delete(0,END)
for row in database.view():
self.list1.insert(END,row)

def search_command(self):
self.list1.delete(0,END)
for row in database.search(self.title_text.get(),self.author_text.get(),self.year_text.get(),self.isbn_text.get()):
self.list1.insert(END,row)

def add_command(self):
database.insert(self.title_text.get(),self.author_text.get(),self.year_text.get(),self.isbn_text.get())
self.list1.delete(0,END)
self.list1.insert(END,(self.title_text.get(),self.author_text.get(),self.year_text.get(),self.isbn_text.get()))

def delete_command(self):
database.delete(self.selected_tuple[0])

def update_command(self):
database.update(self.selected_tuple[0],self.title_text.get(),self.author_text.get(),self.year_text.get(),self.isbn_text.get())

window=Tk()
Window(window)
window.mainloop()