How to save changes to two tables in same transaction on the server

Below are two examples.

In the first example each apply method gets its own connection from connection pool and commits it after saving changes to the database.

In the second example the connection is received from connection pool and passed to each apply method so changes are committed at the end.

import datetime

def change_invoice_date(item, invoice_id):
    now = datetime.datetime.now()

    invoices = item.task.invoices.copy(handlers=False)
    invoices.set_where(id=invoice_id)
    invoices.open()
    invoices.edit()
    invoices.invoice_date.value = now
    invoices.post()
    invoices.apply()

    customer_id = invoices.customer.value
    customers = item.task.customers.copy(handlers=False)
    customers.set_where(id=customer_id)
    customers.open()
    customers.edit()
    customers.last_modified.value = now
    customers.post()
    customers.apply()

import datetime

def change_invoice_date(item, invoice_id):
    now = datetime.datetime.now()

    con = item.task.connect()
    try:
        invoices = item.task.invoices.copy(handlers=False)
        invoices.set_where(id=invoice_id)
        invoices.open()
        invoices.edit()
        invoices.invoice_date.value = now
        invoices.post()
        invoices.apply(con)

        customer_id = invoices.customer.value
        customers = item.task.customers.copy(handlers=False)
        customers.set_where(id=customer_id)
        customers.open()
        customers.edit()
        customers.last_modified.value = now
        customers.post()
        customers.apply(con)

        con.commit()
    finally:
        con.close()