title: System.DBNull error
body: <p>How can I resolve this problem ?why image file making system.dbnull error? </p>
  
  <pre><code>    private void Form1_Load(object sender, EventArgs e)
      {
          SqlDataAdapter da = new SqlDataAdapter("select * from Categories", baglantiYolu);
          DataTable tablo = new DataTable();
          da.Fill(tablo);
          foreach (DataRow kategori in tablo.Rows)
          {
              Kategori k = new Kategori();
              k.KategoriID = int.Parse(kategori["CategoryID"].ToString());
              k.KategoriAdı = kategori["CategoryName"].ToString();
              k.UrunSayisi = UrunSayisiniGetir(int.Parse(kategori["CategoryID"].ToString()));
              k.Aciklama = kategori["Description"].ToString();
              k.Resim = (byte[])kategori["Picture"];
              listBoxKategoriler.Items.Add(k);
          }
      }
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/qnSsL.png" alt="enter image description here"></p>