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 namespace 登录
12 {
13     public partial class Form1 : Form
14     {
15         public Form1()
16         {
17             InitializeComponent();
18         }
19         string ConnStr = "Data Source=.;Initial Catalog=repair;Integrated Security=True";
20         SqlConnection conn = new SqlConnection();
21         public static string name;
22         private void button1_Click(object sender, EventArgs e)
23         {
24
25             if (textBox1.Text != "" && textBox2.Text != "")
26             {
27                 kailu();
28
29                 name = textBox1.Text;
30                 string com = "select count(*) from user_info where userName='" + name + "' ";
31                 SqlCommand comm = new SqlCommand(com, conn);
32                 int a = (int)comm.ExecuteScalar();
33                 if (a == 0)
34                 {
35                     label3.Text = "用户名不存在！";
36                     textBox1.Clear();
37                     textBox2.Clear();
38
39                 }
40                 else
41                 {
42
43                     string corrStr = "select count(*)  from user_info where userName='" + textBox1.Text + "' and  passWord='" + textBox2.Text + "'";
44                     SqlCommand con = new SqlCommand(corrStr, conn);
45                     int tt = (int)con.ExecuteScalar();
46                     if (tt == 0)
47                     {
48                         label3.Text = "您输入的密码有错误，请重新输入！";
49                         textBox2.Clear();
50                     }
51                     else
52                     {
53
54                         label3.Text="恭喜你，登录成功了！";
55                         Form2 foa = new Form2();
56                         foa.ShowDialog();
57                     }
58                 }
59
60
61
62             }
63             else
64             {
65                 MessageBox.Show("请输入用户名和密码！");
66             }
67
68
69         }
70         private void kailu()
71         {
72
73
74             try
75             {
76                 conn = new SqlConnection(ConnStr);
77                 conn.Open();
78             }
79             catch (Exception ex)
80             {
81
82                label3.Text="数据库连接失败" + ex.ToString();
83             }
84
85         }
86
87         private void button2_Click(object sender, EventArgs e)
88         {
89             Form3 form = new Form3();
90             form.ShowDialog();
91         }
92         }
93     }

 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
10 namespace 登录
11 {
12     public partial class Form2 : Form
13     {
14         public Form2()
15         {
16             InitializeComponent();
17         }
18
19         private void Form2_Load(object sender, EventArgs e)
20         {
21             label1.Text = "欢迎你" + Form1.name;
22         }
23     }
24 }

 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
10 namespace 登录
11 {
12     public partial class Form3 : Form
13     {
14         public Form3()
15         {
16             InitializeComponent();
17         }
18
19         private void button1_Click(object sender, EventArgs e)
20         {
21
22             if (textBox1.Text != "" && textBox2.Text != "")
23             {
24                 MessageBox.Show("恭喜你注册成功！");
25             }
26             else
27             {
28                 if (textBox1.Text != "")
29                 {
30                     MessageBox.Show("密码不能为空！");
31                 }
32                 else
33                 {
34                     MessageBox.Show("用户名不能为空！");
35                 }
36             }
37         }
38     }
39 }