title: c# combobox filtering one combobox based on the value of another combobox
body: <p>I have 2 tables, product_items and category.
  And 2 combobox. I want filter another combobox, after selected category.
  Sorry for my bad english speak :), i tryed this 9h, and no solution get :/
  My code how much i have writed.</p>
  
  <pre><code>DataSet ds = new DataSet();
              SqlDataAdapter da = new SqlDataAdapter("select itemid, itemname, pcatid from produkti_items_tab", TestConnection);
              da.Fill(ds, "FillDropDown");
  
              comboBox1.DataSource = ds.Tables["FillDropDown"].DefaultView;
              comboBox1.DisplayMember = "itemname";
              comboBox1.ValueMember = "itemid";
  
              //============================================
              DataSet ddd = new DataSet();
              SqlDataAdapter dada = new SqlDataAdapter("select pcatid, pcatname from produkti_cat_tab", TestConnection);
              dada.Fill(ddd, "FillDropDownzzz");
  
              comboBox2.DataSource = ddd.Tables["FillDropDownzzz"].DefaultView;
              comboBox2.DisplayMember = "pcatname";
              comboBox2.ValueMember = "pcatid";
  </code></pre>
  
  <p>But i dont know what i should write here:</p>
  
  <pre><code>    private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
  {
      //how filter :/
  }
  </code></pre>