auto generate number

Do you want to do this at the client level?

If so use a static member field of int type. And increment it in a getter. Use locking to make it thread safe.

Quickly put together untested sample code:

static class AutoNumber
{
    static object synclock = new object();

    static int number = 0;

    public static int Next
    {
        get
        {
            lock(synclock)
            {
                return ++number;
            }
        }
    }
}

Alternate approach without the lock:

static class AutoNumber
{
    static int number = 0;

    public static int Next
    {
        get
        {
            return Interlocked.Increment(ref number);
        }
    }
}