SqlManage.cs
 1 class SqlManage
 2     {
 3         public static string cnnstring = "Server=wit;Database=test2009;Uid=sa;Pwd=123456;";
 4         public static SqlConnection cnn = null;
 5 
 6         public static DataTable TableSelect(string sql)
 7         {
 8             try
 9             {
 
10                 DataTable table= new DataTable();
11                 SqlDataAdapter sdp = new SqlDataAdapter(sql,SqlManage.cnnstring);
12                 sdp.Fill(table);
13                 return table;
14             }
15             catch (Exception ex)
16             {
17                 MessageBox.Show(ex.Message);
 
18                 return null;
19             }
20         }
21 
22         public static void TableChange(string sql)
23         {
24             try
25             {
26                 SqlCommand cmd = new SqlCommand(sql,SqlManage.cnn);
27                 if (cmd.ExecuteNonQuery() > 0)
 
28                 {
29                     MessageBox.Show("操作成功!");
30                 }
31                 else
32                 {
33                     MessageBox.Show("操作失敗!\n檢查數據庫是否有該記錄");
34                 }
35             }
36             catch (Exception ex)
37             {
38                 MessageBox.Show(ex.Message);
39             }
40         }
41 
42         public static void SetDataGridView(DataGridView d)
43         {
44             d.ReadOnly = true;
45             d.AllowUserToAddRows = false;
46             d.RowHeadersVisible = false;
47             d.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
48         }
49 
50         public static bool JudTextBox(TextBox t)
51         {
52             if (t.Text.Trim().Length < 1)
53             {
54                 return false;
55             }
56             else
57             {
58                 return true;
59             }
60         }
61     }

Program.cs
 1 static void Main()
 2         {
 3             Application.EnableVisualStyles();
 4             Application.SetCompatibleTextRenderingDefault(false);
 5 
 6             try
 7             {
 8                 SqlManage.cnn = new SqlConnection(SqlManage.cnnstring);
 9                 SqlManage.cnn.Open();
10             }
11             catch (Exception ex)
12             {
13                 MessageBox.Show(ex.Message);
14                 return;
15             }
16             Application.Run(new FormMain());
17 
18             SqlManage.cnn.Close();
19         }

C# 創建窗口程序兩個重要文件