Check out example codes for "assign datasource to dropdownlist in c#". It will help you in understanding the concepts better.

Code Example 1

cmd.CommandText = " Select * From GetUsersID";
        cmd.Connection = conn;
        conn.Open();
        DataTable dt  = new DataTable();

        dt.Load(cmd.ExecuteReader());
        conn.Close();

        DropDownList1.DataSource = dt;
        DropDownList1.DataTextField = "Name";
        DropDownList1.DataValueField = "ID";
        DropDownList1.DataBind();

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