Question

I’m having a database where I am constantly putting new data that I get from a service. This is working in a thread, so everytime I see new data I put ii in the database. I am only showing the freshest 20 news in my app, and that is working perfectly. The problem is that I want to delete all the oldest notification from the database, and that only the freshest 20 stay. I don’t know how to write that query. Any help?

Answer 1

Well in the end I’m here to answer my own question 🙂

The thing that i done is this:

if(fetchNotificationsCount() > 20){
        String sql = "SELECT * FROM (SELECT * FROM " + PPASQLiteHelper.TABLE_NOTIFICATIONS + " ORDER BY " + PPASQLiteHelper.COLUMN_ID + " DESC) LIMIT " + fetchNotificationsCount() + " OFFSET 20";
        Cursor cursor = database.rawQuery(sql, null);
        cursor.moveToFirst();
        while(!cursor.isAfterLast()){
            database.delete(PPASQLiteHelper.TABLE_NOTIFICATIONS, PPASQLiteHelper.COLUMN_ID + "=" + cursor.getLong(0), null);
            cursor.moveToNext();
        }
        cursor.close();
    }

With the LIMIT and OFFSET i was able to do what I intended. Thanks for the help anyway.