ASP.NET站点点dorknozzle示例

问题描述

只是从网站点书中做一个例子，我收到错误;

hi just doing an example from the site point book and i am getting an error;

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 20:                 SqlDataReader reader;
Line 21:
Line 22:                 string connectionString =
Line 23:                 ConfigurationManager.ConnectionStrings[
Line 24:                 "Dorknozzle1"].ConnectionString;

can有人请帮助 这是代码 使用System.Data.SqlClient; 使用System.Configuration; 名称空间Dorknozzle { 公共部分类HelpDesk：System.Web.UI.Pa ge { protected void Page_Load（object sender，EventArgs e） { if（！IsPostBack） { SqlConnection conn; SqlCommand categoryComm; SqlCommand subjectComm; SqlDataReader阅读器; string connectionString = ConfigurationManager.ConnectionStrings [ Dorknozzle1]。ConnectionString; conn = new SqlConnection（connectionString）; categoryComm = new SqlCommand（ SELECT CategoryID，Category FROM HelpDeskCategories， conn）; subjectComm = new SqlCommand（ SELECT SubjectID，Subject From HelpDeskSubkects，conn）; t ry { conn.Open（）; reader = categoryComm.ExecuteReader（）; categoryList。 DataSource = reader; categoryList.DataValueField =CategoryID; categoryList.DataTextField =Category; categoryList.DataBind（）; reader.Close（）; reader = subjectComm.ExecuteReader（）; subjectList.DataSource = reader; subjectList.DataValueField =SubjectID; subjectList.DataTextField =Subject; subjectList.DataBind（）; reader。关闭（）; reader = categoryComm.ExecuteReader（）; categoryList.DataSource = reader; categoryList.DataValueField =CategoryID; categoryList.DataTextField =Category; categoryList.DataBind（）; reader.Close（ ）; } 终于 { conn.Close（）; } } } protected void submitButton_Click（object sender，EventArgs e） { if（Page.IsValid） { SqlConnection conn; SqlCommand comm; string connectionString = ConfigurationManager.ConnectionStrings [ Dorknozzle1]。ConnectionString; conn = new SqlConnection（connectionString）; comm = new SqlCommand（ INSERT INTO HelpDesk（EmployeeID，StationNumber，+ CategoryID，SubjectID，Description，StatusID）+ VALUES（@ EmployeeID，@ stationNumber，@ ClassoryID，+ @ SubjectID，@ Description，@ StatusID），conn）; comm.Parameters。添加（@ EmployeeID，System.Data.SqlDbType.Int）; comm.Parameters [@ EmployeeID]。值= 5; comm.Parameters。添加（@ StationNumber， System.Data.SqlDbType.Int）; comm.Parameters [@ StationNumber]。Value = stationTextBox.Text; comm.Parameters.Add（@ CategoryID，System.Data.SqlDbType.Int）; comm.Parameters [@ CategoryID]。值= categoryList.SelectedItem.Value; comm.Parameters.Add（@ SubjectID，System .Data.SqlDbType.Int）; comm.Parameters [@ SubjectID]。值= subjectList.SelectedItem.Value; comm.Parameters.Add（@ Description， System.Data.SqlDbType.NVarChar，50）; comm.Parameters [@ Description]。Value = descriptionTextBox.Text; comm.Parameters.Add（@ StatusID，System.Data.SqlDbType.Int）; comm。参数[@ StatusID]。值= 1; 尝试 { conn.Open（）; comm.ExecuteNonQuery（）; Response.Redirect（HelpDesk.aspx）; } catch { dbErrorMessage.Text = 提交服务台请求时出错！请+ 稍后再试，和/或更改输入的数据！; } 终于 { conn.Close（）; } } } } }

can anybody help please this is the code using System.Data.SqlClient; using System.Configuration; namespace Dorknozzle { public partial class HelpDesk : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { SqlConnection conn; SqlCommand categoryComm; SqlCommand subjectComm; SqlDataReader reader; string connectionString = ConfigurationManager.ConnectionStrings[ "Dorknozzle1"].ConnectionString; conn = new SqlConnection(connectionString); categoryComm = new SqlCommand( "SELECT CategoryID, Category FROM HelpDeskCategories", conn); subjectComm = new SqlCommand( "SELECT SubjectID, Subject FROM HelpDeskSubkects", conn); try { conn.Open(); reader = categoryComm.ExecuteReader(); categoryList.DataSource = reader; categoryList.DataValueField = "CategoryID"; categoryList.DataTextField = "Category"; categoryList.DataBind(); reader.Close(); reader = subjectComm.ExecuteReader(); subjectList.DataSource = reader; subjectList.DataValueField = "SubjectID"; subjectList.DataTextField = "Subject"; subjectList.DataBind(); reader.Close(); reader = categoryComm.ExecuteReader(); categoryList.DataSource = reader; categoryList.DataValueField = "CategoryID"; categoryList.DataTextField = "Category"; categoryList.DataBind(); reader.Close(); } finally { conn.Close(); } } } protected void submitButton_Click(object sender, EventArgs e) { if (Page.IsValid) { SqlConnection conn; SqlCommand comm; string connectionString = ConfigurationManager.ConnectionStrings[ "Dorknozzle1"].ConnectionString; conn = new SqlConnection(connectionString); comm = new SqlCommand( "INSERT INTO HelpDesk (EmployeeID, StationNumber, " + "CategoryID, SubjectID, Description, StatusID) " + "VALUES (@EmployeeID, @StationNumber, @CategoryID, " + "@SubjectID, @Description, @StatusID)", conn); comm.Parameters.Add("@EmployeeID", System.Data.SqlDbType.Int); comm.Parameters["@EmployeeID"].Value = 5; comm.Parameters.Add("@StationNumber", System.Data.SqlDbType.Int); comm.Parameters["@StationNumber"].Value = stationTextBox.Text; comm.Parameters.Add("@CategoryID", System.Data.SqlDbType.Int); comm.Parameters["@CategoryID"].Value = categoryList.SelectedItem.Value; comm.Parameters.Add("@SubjectID", System.Data.SqlDbType.Int); comm.Parameters["@SubjectID"].Value = subjectList.SelectedItem.Value; comm.Parameters.Add("@Description", System.Data.SqlDbType.NVarChar, 50); comm.Parameters["@Description"].Value = descriptionTextBox.Text; comm.Parameters.Add("@StatusID", System.Data.SqlDbType.Int); comm.Parameters["@StatusID"].Value = 1; try { conn.Open(); comm.ExecuteNonQuery(); Response.Redirect("HelpDesk.aspx"); } catch { dbErrorMessage.Text = "Error submitting the help desk request! Please " + "try again later, and/or change the entered data!"; } finally { conn.Close(); } } } } }

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