import random

while True:
    generated_barcode = '%012d' % random.randrange(1, 10**12)
    # check if this barcode already exists (veeeery very low probability although)
    barcode_from_db = sql.find_user_code(generated_barcode)
    if barcode_from_db:
        log.warning('O_o!!!! GENERATED BARCODE ALREADY EXISTS!!!! Have to generate another one...')
        log.warning('  look at this: ' + str(barcode_from_db))
    else:
        break