UART.setup("UART1")
with serial.Serial(port="/dev/ttyO1", baudrate=9600) as ser:
    while True:
        amount = server.recv(1024).decode()
        data = ser.read().decode("ascii")
        if sql.execute("select count(*) from klienci where klient =" + data) == 0:
            sql.execute("insert into klienci values(" + data + "," + amount + ")")
        elif sql.execute("select amount from klienci where klient =" + data) >= amount:
            sql.execute("update klienci set amount =" + amount + " where klient =" + data)
            server.send("Transakcja zaakceptowana")
        else:
            server.send("Transakcja odrzucona")