检查文件是否存在的代码（C#.net)

 

 1       private void button1_Click(object sender, EventArgs e)
 2        {
 3
 4                cn.ConnectionString = this.textBox1.Text;
 5                cn.Open();
 6               System.Data.DataTable dt = SqlHelper.ExecuteDataset(cn, CommandType.Text, " select * from [Resource_Files]").Tables[0];
 7                this.progressBar1.Maximum = dt.Rows.Count;
 8                for (int i = 0; i < dt.Rows.Count; i++)
 9                {
10                    int ID = Convert.ToInt32(dt.Rows[i]["FileId"]);
11                    string path = dt.Rows[i]["FileName"].ToString() +"."+ dt.Rows[i]["Extend"].ToString() ;
12                    string SQL = string.Empty;
13                    path = @"F:\upfile\UploadFiles\" + path.Substring(0, 1) + @"\" + path;
14                    if (File.Exists(path))
15                    {
16                        SQL = "update [Resource_Files] set [isExists]=1 where FileId= " + ID;
17                    }
18                    else
19                    {
20                        SQL = "update [Resource_Files] set [isExists]=0 where FileId= " + ID;
21                    }
22                    this.richTextBox1.Text = SQL+" path: "+path;
23                    SqlHelper.ExecuteNonQuery(cn, CommandType.Text, SQL);
24                    this.progressBar1.Value++;
25                    this.progressBar1.Refresh();
26                    this.richTextBox1.Refresh();
27                    Application.DoEvents();
28                }
29                cn.Close();
30                MessageBox.Show("完成！");
31
32
33
34        }