Double insert into listbox SQLITE3 & TKINTER

In accordance with https://pynative.com/python-sqlite-insert-into-table/, you can also use following:

rows = cursor.fetchall() instead of rows = cursor.execute("SELECT * FROM informations") ?

Then also close the cursor object afterwards with cursor.close().

Generally it,s also good to use a try-catch block around your CUD-operations , so you will be able to handle checked exceptions.

Hopefully, this will help!

It is because you forgot to clear the listbox list_1 before propagating data from the table:

def save_register():    firstname = entry_firstname.get()    name = entry_name.get()    adress = entry_adress.get()    phone = entry_phone.get()    connection = sql3.connect("gestionnaire.db")    cursor = connection.cursor()    cursor.execute("INSERT INTO informations ('FirstName', 'Name', 'Adress', 'Phone') VALUES (?,?,?,?)", (firstname, name, adress, phone))    connection.commit()    list_1.delete(0, "end") # clear list_1    rows = cursor.execute("SELECT * FROM informations")    for row in rows:        list_1.insert(END, row)

Or just append the new record to list_1:

def save_register():    firstname = entry_firstname.get()    name = entry_name.get()    adress = entry_adress.get()    phone = entry_phone.get()    connection = sql3.connect("gestionnaire.db")    cursor = connection.cursor()    cursor.execute("INSERT INTO informations ('FirstName', 'Name', 'Adress', 'Phone') VALUES (?,?,?,?)", (firstname, name, adress, phone))    connection.commit()    # insert new record into list_1    list_1.insert(END, (cursor.lastrowid, firstname, name, adress, phone))

There is another issue in delete_register(): it will remove all records in informations table other than the selected record in list_1. You need to add a WHERE clause in the DELETE SQL statement:

def delete_register():    index = list_1.curselection()    if index:        recid = list_1.get(index)[0]  # get the unique ID of the selected record        connection = sql3.connect("gestionnaire.db")        cursor = connection.cursor()        for row in index:            cursor.execute("DELETE FROM informations WHERE id = ?", (recid,)) # delete selected record            list_1.delete(row)        connection.commit()