Question

如何绑定产品名称，然后在标签结果中获取产品ID和价格？这三个属性来自DB中的同一个表。

代码：

public partial class CreateOrder : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Page.IsPostBack == false) bindListBox();
    }
}

private void bindListBox()
{
    ddlProduct.DataSource     = getReader();
    ddlProduct.DataTextField  = "productName";
    ddlProduct.DataValueField = "IDANDPRICE"; 

    ddlProduct.DataBind();
}

private SqlDataReader getReader()
{
    //get connection string from web.config
    string strConnectionString =
        ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
    SqlConnection myConnect = new SqlConnection(strConnectionString);

    string strCommandText = "SELECT productName, productID,productPrice,(productID + '-' +  productPrice) AS IDANDPRICE from Product";
    SqlCommand cmd = new SqlCommand(strCommandText, myConnect);

    myConnect.Open();

    SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
    return reader;
}

protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
{
    Label1.Text = "";
    Label1.Text += "productName:" + ddlProduct.SelectedItem.Text + "<br/>";

    Label2.Text = "";
    Label2.Text += "IDANDPRICE:" + ddlProduct.SelectedItem.ToString() ;

}

Answer 1

I find the following errors:  

1- cast number filed to nvarchar in sql query
2- set AutoPostBack property of listbox to true
3- use ddlProduct.SelectedItem.Value for label2

我创建了一个页面并使用您的代码并应用了上述建议，以下代码完美无缺。

public partial class _Default : System.Web.UI.Page
{

protected void Page_Load(object sender, EventArgs e)
{
    if (Page.IsPostBack == false) bindListBox();
}

private void bindListBox()
{
    ddlProduct.DataSource = getReader();
    ddlProduct.DataTextField = "name";
    ddlProduct.DataValueField = "IdAndName";

    ddlProduct.DataBind();
}

private SqlDataReader getReader()
{
    //get connection string from web.config
    string strConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
    SqlConnection myConnect = new SqlConnection(strConnectionString);

    string strCommandText = "SELECT Id,Name,CAST( id as nvarchar(10) )+'-'+Name as IdAndName  FROM  Product";
    SqlCommand cmd = new SqlCommand(strCommandText, myConnect);

    myConnect.Open();

    SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
    return reader;
}

protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
{
    Label1.Text = "";
    Label1.Text += "productName:" + ddlProduct.SelectedItem.Text + "<br/>";

    Label2.Text = "";
    Label2.Text += "IDANDPRICE:" + ddlProduct.SelectedItem.Value;
}

}

如何放两个DataValueFields？

1 个答案: