In my project, I am trying to populate ComboBox from DataSet. I succeeded in populating but the values inside the ComboBox are not distinct (Because it just showing the values present in DataSet). I cant bind the ComboBox to DataSet because I am adding "Select" text at first of populating the values. Here is my code.

        ComboBox --> cmb
        DataSet --> ds
        DataSet Column Name --> value(string)

        cmb.Items.Clear();
        cmb.Items.Add("Select");
        for (int intCount = 0; intCount < ds.Tables[0].Rows.Count; intCount++)
        {
            cmb.Items.Add(ds.Tables[0].Rows[intCount][value].ToString());
        }
        cmb.SelectedIndex = 0;

My question is how to allow distinct values (or restrict duplicate values) inside the ComboBox.