fine.py

from tkinter import *
from tkinter import ttk
from tkinter import messagebox
import sqlite3
from sqlite3 import Error
import re
import sys,os
py = sys.executable


#creating window
class Fine(Tk):
    def __init__(self):
        super().__init__()
        self.iconbitmap(r'libico.ico')
        self.maxsize(500, 300)
        self.minsize(500, 300)
        self.title("Clear Fine")
        #creating variables
        a = StringVar()
        def clear():
            if len(a.get()) == 0:
                messagebox.showerror("Error","Please Enter The Id")
            elif a.get().isdigit():
                try:
                    self.conn = sqlite3.connect('library_administration.db')
                    self.myCursor = self.conn.cursor()
                    self.myCursor.execute("Select Student_Id from students")
                    student = self.myCursor.fetchall()
                    listStudent = list(student)
                    if listStudent:
                        for sid in listStudent:
                            if int(a.get()) in sid:
                                con = messagebox.askyesno("Confirm","Are You Sure you want to clear the fine?")
                                if con:
                                    self.myCursor.execute("Update students set Fine = 0 where Student_Id = ?",[a.get()])
                                    self.conn.commit()
                                    self.conn.close()
                                    messagebox.showinfo("Successful","All Fine Cleared")
                                    d = messagebox.askyesno("Confirm","Do you want to clear another fine?")
                                    if d:
                                        self.destroy()
                                        os.system('%s %s'% (py,'fine.py'))
                                    else:
                                        self.destroy()
                            else:
                                messagebox.showinfo("Oops","The Id you entered is not found")
                    else:
                        messagebox.showerror("Error","Please Check The Id")
                except:
                    messagebox.showinfo("Oops","Something Goes Wrong")
            else:
                messagebox.showerror("Error","Please Check The Id")               
        Label(self,text="Enter Student Id", font = ('arial',15,'bold')).place(x=50,y=100)
        Entry(self,textvariable=a,width=40).place(x=230,y=105)
        Button(self, text='Clear Fine', width=20,command = clear).place(x=230, y=155)
Fine().mainloop()