我得到错误“对象引用未设置为对象的实例”当我运行此代码时，L可以做什么来摆脱这个。 [英] I Am Getting The Error "Object Reference Not Set To An Instance Of An Object" While I Run This Code, L What Can Be Done To Get Rid Of This.
问题描述
CS代码
使用系统;
使用System.Collections .Generic;
使用System.Linq;
使用System.Web;
使用System.Web.UI;
使用System.Web.UI.WebControls;
公共部分类WebForm：System.Web.UI.Page
{
protected void Page_Load（object sender，EventArgs e）
{
}
protected void Button1_Click（object sender，EventArgs e）
{
ConnectionClass obj = new ConnectionClass（）;
obj.Connection（）;
obj.cmd.CommandText =sp_getstudentdata;
obj.con.Open（）;
obj.dr = obj.cmd.ExecuteReader （）;
if（obj.dr.HasRows）
{
this.GridView1.DataSource = obj.dr;
this.GridView1.DataBind（）;
}
else
{
Response.Write（未找到数据）;
}
obj.dr.Close（ ）;
obj.con.Close（）;
}
}
HTML CODE
<！DOCTYPE html>
< html xmlns =http://www.w3.org/1999/xhtml>
< head runat =server>
< title>< / title>
< / head>
< body>
< form id =form1runat =server>
< div>
< asp：TextBox ID =TextBox1runat =server>< / asp：TextBox>
& nbsp;< asp：Button ID = Button1runat =serverOnClick =Button1_ClickText =Button/>
< br />
< br />
< asp：GridView ID =GridView1runat =serverCellPadding =4ForeColor =＃333333GridLines =None>
< AlternatingRowStyle BackColor =WhiteForeColor =＃284775/>
< EditRowStyle BackColor =＃999999/>
< FooterStyle BackColor =＃5D7B9DFont-Bold =TrueForeColor =White/>
< HeaderStyle BackColor =＃5D7B9DFont-Bold =True ForeColor =白色/>
< PagerStyle BackColor =＃284775ForeColor =WhiteHorizontalAlign =Center/>
< RowStyle BackColor =＃F7F6F3ForeColor =＃333333/>
< SelectedRowStyle BackColor =＃E2DED6Font-Bold =TrueForeColor =＃333333/>
< SortedAscendingCellStyle BackColor =＃E9E7E2/>
< SortedAscendingHeaderStyle BackColor =＃506C8C/>
< SortedDescendingCellStyle BackColor = ＃FFFDF8/>
< SortedDescendingHeaderStyle BackColor =＃6F8DAE/>
< / asp：G ridView>
< / div>
< / form>
< / body>
< / html>
连接类
使用System;
使用System.Collections.Generic;
使用System.Linq;
使用System.Web;
使用System.Data;
使用System.Data.SqlClient;
///< summary>
/// ConnectionClass的摘要说明
///
公共类ConnectionClass
{
public SqlConnection con;
public SqlCommand cmd;
public SqlDataReader dr;
public void Connection（ ）
{
SqlConnection con = new SqlConnection（Data source = ASHOK-PC; integrated security = true; initial catalog = db）;
SqlCommand cmd = new SqlCommand（）;
cmd.CommandType = CommandType.StoredProcedure;
}
}
CS Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class WebForm : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
ConnectionClass obj = new ConnectionClass();
obj.Connection();
obj.cmd.CommandText = "sp_getstudentdata";
obj.con.Open();
obj.dr = obj.cmd.ExecuteReader();
if (obj.dr.HasRows)
{
this.GridView1.DataSource = obj.dr;
this.GridView1.DataBind();
}
else
{
Response.Write("No Data Found");
}
obj.dr.Close();
obj.con.Close();
}
}
HTML CODE
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
<br />
<br />
<asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None">
<AlternatingRowStyle BackColor="White" ForeColor="#284775" />
<EditRowStyle BackColor="#999999" />
<FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
<RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
<SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
<SortedAscendingCellStyle BackColor="#E9E7E2" />
<SortedAscendingHeaderStyle BackColor="#506C8C" />
<SortedDescendingCellStyle BackColor="#FFFDF8" />
<SortedDescendingHeaderStyle BackColor="#6F8DAE" />
</asp:GridView>
</div>
</form>
</body>
</html>
Connection Class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Data.SqlClient;
/// <summary>
/// Summary description for ConnectionClass
///
public class ConnectionClass
{
public SqlConnection con;
public SqlCommand cmd;
public SqlDataReader dr;
public void Connection()
{
SqlConnection con = new SqlConnection("Data source=ASHOK-PC;integrated security=true;initial catalog=db");
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.StoredProcedure;
}
}
推荐答案
修改sqlconnection。也可以设置db的用户名和密码
modify the sqlconnection .also set the username and password of your db
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