sql注入

 1 using System;
 2 using System.Collections.Generic;
 3 using System.ComponentModel;
 4 using System.Data;
 5 using System.Drawing;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Windows.Forms;
 9 using System.Data.SqlClient;
10 
11 
12 namespace sql注入
13 {
14     public partial class Form1 : Form
15     {
16         public Form1()
17         {
18             InitializeComponent();
19         }
20 
21         private void btnLogin_Click(object sender, EventArgs e)
22         {
23             object obj;
24             //Data Source=.;Initial Catalog=mysql;Integrated Security=True
25             string str = "Data Source =.;Initial Catalog = mysql; Integrated Security = True; ";
26             //下面这种字符串拼接的方式会被   xx' or 1=1 -- 的用户名给注入，所以不能使用
27             //string sql = string.Format("select count(*) from users where name = '{0}' and password = '{1}'",txtName.Text,txtPwd.Text);
28             //使用参数的方法可以避免注入
29             string sql = "select count(*) from users where name = @name and password = @password";
30             using (SqlConnection con = new SqlConnection(str))
31             {
32                 using (SqlCommand cmd = new SqlCommand(sql, con))
33                 {
34                     con.Open();
35                     //cmd使用参数
36                     cmd.Parameters.AddWithValue("@name", txtName.Text);
37                     cmd.Parameters.AddWithValue("@password", txtPwd.Text);
38                     obj = cmd.ExecuteScalar();
39                     if (Convert.ToInt32(obj) > 0)
40                     {
41                         MessageBox.Show("登录成功");
42                     }
43                     else
44                     {
45                         MessageBox.Show("登录失败");
46                     }
47 
48                 }
49             }
50 
51 
52         }
53     }
54 }