c# - 根据下拉选择将 ID 保存到数据库

Question

我使用以下代码将 BusinessID 绑定(bind)为 ddlIndustry 下拉列表的 DataValueField。我想要做的是将选定的 ID 保存到不同的表(公司)。我正在使用 ddlIndustry.SelectedValue 执行此操作。由于某种原因，第一个值总是被保存 (1)，而不是选定的值。对于为什么会发生这种情况，您有什么想法吗？

protected void Page_Load(object sender, EventArgs e)
{

    if (!Page.IsPostBack)
        BindCountry();
        BindIndustry();
}

private void BindCountry()
{
    XmlDocument doc = new XmlDocument();
    doc.Load(Server.MapPath("countries.xml"));

    foreach (XmlNode node in doc.SelectNodes("//country"))
    {
        ddlCountry.Items.Add(new ListItem(node.InnerText, node.Attributes["code"].InnerText));
        ddlCountry.SelectedIndex = 94;
    }
}

private void BindIndustry()
{
    SqlCommand cmd = null;

    SqlConnection conn = new SqlConnection(GetConnectionString());
    conn.Open();

    cmd = new SqlCommand("Select Industry, BusinessID FROM BusinessType", conn);

    cmd.CommandType = CommandType.Text;

    SqlDataAdapter da = new SqlDataAdapter(cmd);

    DataSet ds = new DataSet();

    da.Fill(ds);

    conn.Close();

    ddlIndustry.DataSource = ds;
    ddlIndustry.DataTextField = "Industry";
    ddlIndustry.DataValueField = "BusinessID";
    ddlIndustry.DataBind();

    //ddlIndustry.Items.Insert(0, new System.Web.UI.WebControls.ListItem("-- Please Select Industry --", "0"));

}

private void ExecuteCompanyDetailsInsert()
{

    SqlConnection conn = new SqlConnection(GetConnectionString());



    string sql = "INSERT INTO Company (BusinessID, CompanyName, Email, AddressLine1, AddressLine2, Location, Telephone) VALUES "
                + " (@BusinessID, @CompanyName, @Email, @AddressLine1, @AddressLine2, @Location, @Telephone)";

    try
    {

        conn.Open();
        SqlCommand cmd = new SqlCommand(sql, conn);
        SqlParameter[] param = new SqlParameter[7];

        param[0] = new SqlParameter("@BusinessID", SqlDbType.Int);
        param[1] = new SqlParameter("@CompanyName", SqlDbType.VarChar, 50);
        param[2] = new SqlParameter("@Email", SqlDbType.VarChar, 50);
        param[3] = new SqlParameter("@AddressLine1", SqlDbType.VarChar, 50);
        param[4] = new SqlParameter("@AddressLine2", SqlDbType.VarChar, 50);
        param[5] = new SqlParameter("@Location", SqlDbType.VarChar, 50);
        param[6] = new SqlParameter("@Telephone", SqlDbType.VarChar, 50);

        param[0].Value = ddlIndustry.SelectedValue;
        param[1].Value = company_name.Text;
        param[2].Value = company_email.Text;
        param[3].Value = address_line_1.Text;
        param[4].Value = address_line_2.Text;
        param[5].Value = ddlCountry.SelectedItem.Text;
        param[6].Value = telephone.Text;

        for (int i = 0; i < param.Length; i++)
        {
            cmd.Parameters.Add(param[i]);
        }

        cmd.CommandType = CommandType.Text;
        cmd.ExecuteNonQuery();

    }

    catch (System.Data.SqlClient.SqlException ex)
    {

        string msg = "Insert Error:";
        msg += ex.Message;
        throw new Exception(msg);
    }

    finally
    {
        conn.Close();
    }

}

Answer 1

首先修改这段代码，因为当你的页面回发到服务器时，你的industry dropdown再次绑定(bind)，你的selected value丢失了

if (!Page.IsPostBack)
{
    BindCountry();
    BindIndustry();
}

然后你可以得到选择的值

ddlIndustry.SelectedValue