给DropDownList的DataTextField属性绑定两个字段

using (SqlConnection conn = new SqlConnection("server=(local);database=Northwind;user id=sa;password=sa;min pool size=4;max pool size=100;Connection Lifetime=30;"))
{
    SqlDataAdapter adapter1 = new SqlDataAdapter("Select Top 10 ProductId,ProductName+','+convert(nvarchar,UnitPrice) Text FROM Products", conn);
    DataTable table1 = new DataTable();
    adapter1.Fill(table1);

    DropDownList1.DataSource = table1.DefaultView;
    DropDownList1.DataTextField = "Text";
    DropDownList1.DataValueField = "ProductId";
    DropDownList1.DataBind();
}

using (SqlConnection conn = new SqlConnection("server=(local);database=Northwind;user id=sa;password=sa;min pool size=4;max pool size=100;Connection Lifetime=30;"))
{
    SqlDataAdapter adapter1 = new SqlDataAdapter("Select Top 10 ProductId,ProductName,UnitPrice FROM Products", conn);
    DataTable table1 = new DataTable();
    adapter1.Fill(table1);

    table1.Columns.Add("Text", System.Type.GetType("System.String"), "ProductName+'-'+UnitPrice");

    DropDownList1.DataSource = table1.DefaultView;
    DropDownList1.DataTextField = "Text";
    DropDownList1.DataValueField = "ProductId";
    DropDownList1.DataBind();
}