Hvordan undersøger jeg om der kommet nyt datasæt i databasen?

public class SleepLoop {
    private static void dosomething() throws InterruptedException {
        // simulate that it takes some time
        Thread.sleep(100);
    }
    public static void main(String[] args) throws InterruptedException {
        long t = System.currentTimeMillis();
        while(true) {
            dosomething();
            Thread.sleep(1000);
            long t2 = System.currentTimeMillis();
            System.out.printf("%5.3f seconds\n", (t2 - t)/1000.0);
            t = t2;
        }
    }
}

import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;

public class RealTimer {
    public static void main(String[] args) throws IOException {
        Timer timer = new Timer();
        timer.schedule(new DoSomethingTask(), 1000, 1000);
        System.in.read();
        timer.cancel();
    }
}

class DoSomethingTask extends TimerTask {
    private long t;
    public DoSomethingTask() {
        t = System.currentTimeMillis();
    }
    private static void dosomething() throws InterruptedException {
        // simulate that it takes some time
        Thread.sleep(100);
    }
    public void run() {
        try {
            dosomething();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        long t2 = System.currentTimeMillis();
        System.out.printf("%5.3f seconds\n", (t2 - t)/1000.0);
        t = t2;
    }
}