[Tkinter] Updating a Label with new information

[LucasRibeiro]

I am building a program that makes a SELECT on my database on my local machine. In this program, I have a menu, and in it, I created a function called SELECT. However, when I select this option again, it creates a new Label just below it, and I just want to update the Label. Below are the ScreenShots of the program and the source code. I was wondering if anyone could help me solve this problem. Thank you!

from tkinter import *
import psycopg2 # LIBRARY FOR CONNECT TO THE POSGRESQL DB

root = Tk()
root.geometry('1000x500')
menubar = Menu(root)

con = psycopg2.connect( # LOCAL POSTGRESQL DB CONNECTION
    host="localhost",
    database="escola",
    user="postgres",
    password=248657
)


def select(): 
    v = StringVar()

    cur = con.cursor() # CREATING A CURSOR
    cur.execute("SELECT id, nome, dt_nasc, nome_mae, nome_pai FROM alunos") # QUERY

    rows = cur.fetchall()

    separator = '+----+-----------------------------+--------------------+-----------------------------+-----------------------------+'
    prep_string = ''''''

    prep_string = '''{}{}\n'''.format(prep_string, separator)
    prep_string = '''{}{}\n'''.format(prep_string, '|ID'.ljust(5) + '| Nome'.ljust(30) + '| Data de Nascimento |'.ljust(
        21) + ' Nome da Mãe'.ljust(29) + '| Nome do Pai'.ljust(30) + '|')
    prep_string = '''{}{}\n'''.format(prep_string, separator)
    for r in rows:
        prep_string = '''{}{}\n'''.format(prep_string,
                                          f'|{r[0]}'.ljust(5) + f'|  {r[1]}'.ljust(30) + f'|  {r[2]}'.ljust(
                                              21) + f'|      {r[3]}'.ljust(30) + f'|  {r[4]}'.ljust(30) + '|')
    prep_string = '''{}{}\n'''.format(prep_string, separator)

    v.set(prep_string)

    cur.close()

    box = Label(root, textvariable=v, font='TkFixedFont').pack() # THE LABEL

# THE MENU

file = Menu(menubar, tearoff=0)
menubar.add_cascade(label="Principal", menu=file)
file.add_command(label="SELECT", command=select)
file.add_command(label="Exit", command=root.quit)

root.config(menu=menubar)
root.mainloop()

[Yoriz]

Move these two lines

v = StringVar()
box = Label(root, textvariable=v, font='TkFixedFont').pack() # THE LABEL

outside of the function so they are only created once before hand

The

v.set(prep_string)

will update the value in same place

[LucasRibeiro]

Move these two lines

v = StringVar()
box = Label(root, textvariable=v, font='TkFixedFont').pack() # THE LABEL

outside of the function so they are only created once before hand

The

v.set(prep_string)

will update the value in same place

Thank you, Yoriz! It's done.