我是 .NET 的初学者，并且在我在 page_load 上定义的单选按钮索引更改事件处理程序中使用 sql 连接时遇到了困难。
下面是我的代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Configuration;
namespace Controls
{
public partial class Report_Selection : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
GridView1.HeaderStyle.Font.Bold = true;
RadioButtonList1.SelectedIndexChanged += new EventHandler(RadioButtonList1_SelectedIndexChanged);
using (SqlConnection cnn = new SqlConnection("Data Source=DBSW9079;Initial Catalog=Underwriting;Integrated Security=SSPI;"))
{
SqlCommand cmd;
SqlDataReader sdr;
if (!IsPostBack)
{
cmd = new SqlCommand("select Categoryid,CategoryTitle from Report_Category", cnn);
cnn.Open();
sdr = cmd.ExecuteReader();
SelectCategorydlist1.DataSource = sdr;
SelectCategorydlist1.DataTextField = "CategoryTitle";
SelectCategorydlist1.DataValueField = "categoryid";
SelectCategorydlist1.DataBind();
cnn.Close();
}
else
{
//It's a Post back
//make the grid visible and fill it
GridView1.Visible = true;
RadioButtonList1.SelectedValue = "1";
cmd = new SqlCommand("Select rptdesc,rptdesctext,categoryid from report_description " + "where categoryid != 99999"
+ "and categoryid = " + Convert.ToInt32(SelectCategorydlist1.SelectedValue).ToString(), cnn);
cnn.Open();
sdr = cmd.ExecuteReader();
GridView1.DataSource = sdr;
GridView1.DataBind();
sdr.Close();
{
}
}
}
}
void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
SqlCommand cmd1;
SqlDataReader sdr1;
if (RadioButtonList1.SelectedIndex.Equals(1))
{
RadioButtonList1.ClearSelection();
cmd1 = new SqlCommand("Select rptdesc,rptdesctext,categoryid from report_description "
+ "and categoryid = " + Convert.ToInt32(SelectCategorydlist1.SelectedValue).ToString(), cnn);
cnn.Open();
sdr1= cmd1.ExecuteReader();
GridView1.DataSource = sdr1;
GridView1.DataBind();
sdr1.Close();
}
}
}
}
在上面的代码中，当我在事件处理程序中使用 cnn sequel 连接时，我得到一个小 r