public void TestUpdate()
        {
            ImageRecord ir;
            using (ZumpaDB db = new ZumpaDB())
            {
                ir = new ImageRecord { File = "File", Link = "Link", Size = 12345, IsValid = true };
                db.Images.InsertOnSubmit(ir);
                db.SubmitChanges();
            }

            using (ZumpaDB db = new ZumpaDB())
            {
                ir = db.Images.Where(e => "File".Equals(e.File)).SingleOrDefault();
                Assert.IsNotNull(ir);
                ir.IsValid = false;
                db.SubmitChanges();
            }

            using (ZumpaDB db = new ZumpaDB())
            {
                ir = db.Images.Where(e => "File".Equals(e.File)).FirstOrDefault();
                Assert.IsFalse(ir.IsValid);
                db.Images.DeleteOnSubmit(ir);
                db.SubmitChanges();
            }
        }
 /// <summary>
 /// Save record to db
 /// </summary>
 /// <param name="link"></param>
 /// <param name="file"></param>
 /// <param name="size"></param>
 private ImageRecord SaveLinkToDb(string link, string file, long size)
 {
     ImageRecord rec = new ImageRecord { Link = link, File = file, Size = size, IsValid = true };
     ZumpaDB.Instance.Images.InsertOnSubmit(rec);
     ZumpaDB.Instance.SubmitChanges();
     return rec;
 }
 /// <summary>
 /// Call this if link doesn't target image
 /// </summary>
 /// <param name="link"></param>
 public void NotifyInvalidLink(string link)
 {
     ImageRecord item = null;
     if (_cache.TryGetValue(link, out item))
     {
         if (item.IsValid)
         {
             item.IsValid = false;
             ZumpaDB.Instance.SubmitChanges();
         }
     }
     else
     {
         //it was completely problem with loading
         ImageRecord ir = new ImageRecord{Link = link, File = "", Size = 0, IsValid = false};
         _cache[link] = ir;
         ZumpaDB.Instance.Images.InsertOnSubmit(ir);
         ZumpaDB.Instance.SubmitChanges();
     }
 }