在Asp.Net中执行Connectins我遇到错误，在执行Codi时我得到空参考异常 [英] Excuting Connectins In Asp.Net I Am Getting Error, I Am Getting Null Reference Exception When Excuting The Codi

问题描述

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindGridView();
        }
    }

    protected void BindGridView()
    {
        DataTable dt = new DataTable();
        SqlDataAdapter da = new SqlDataAdapter("Select eid,ename,age from emp", con);
        con.Open();
        da.Fill(dt);
        con.Close();

        if (dt.Rows.Count > 0)
        {
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
    }
    
    protected void GridView1_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
    {
        TextBox txt_name = new TextBox();
        TextBox txt_age = new TextBox();

        TextBox txt_id = new TextBox();
        txt_id = (TextBox)GridView1.FooterRow.FindControl("txt_eid");
        txt_name = (TextBox)GridView1.FooterRow.FindControl("txt_ename");
        txt_age = (TextBox)GridView1.FooterRow.FindControl("txt_eage");

        SqlCommand cmd = new SqlCommand("insert into emp(eid,ename,age)values('" + txt_id.Text + "','" + txt_name.Text + "','" + txt_age.Text + "')");

        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
        BindGridView();
    }
        
}

推荐答案

首先，你应该使用参数化查询以避免 SQL注入攻击。



接下来，它提供 NullReference 异常，因为 TextBoxes 本身是 null 。这意味着它无法为您找到 TextBoxes 。

First of all, you should use Parameterized query to avoid SQL Injection attacks.

Next, it is giving NullReference Exception, because the TextBoxes are itself null. That means it failed to find the TextBoxes for you.

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