ASP.NET数据库存取图片的方法

CREATE TABLE Images
( 
Roll_no varchar(12) primary key,
Name_File varchar(100),
Extension varchar(100) , 
img varbinary(max) ,
Img_date datetime 
) 

文件序号
<asp:TextBox ID="txtrollno" runat="server">
</asp:TextBox>
<br />

选择文件
<asp:FileUpload ID="FileUpload1" runat="server" />
<br />

<asp:Button ID="Button1" runat="server"
Text="上传" OnClick="Button1_Click" />

using System;
using System.Data;
using System.Data.SqlClient;
using System.IO;
using System.Web; 

protected void Button1_Click(object sender, EventArgs e)
{
 if (!FileUpload1.HasFile) 
  {
  Response.Write("未选择文件");
  return;
  }


  else
  {
  //创建访问上传文件的对象，并获取上传的文件
  HttpPostedFile file = FileUpload1.PostedFile;

  //获取上传文件的文件名和扩展名
  string filename = Path.GetFileName(FileUpload1.PostedFile.FileName); 
  string extension = Path.GetExtension(filename); 
  
  //实例化一个byte数组，其长度等于上传文件的长度
  byte[] imagetype = new byte[file.ContentLength];
  
  //将文件数据读取到byte数组中
  file.InputStream.Read(imagetype, 0, file.ContentLength); 

  //判断图片格式
  if ((extension == ".jpg") || (extension == ".png") || (extension == ".gif") || (extension == ".bmp"))
  {
   //表里写入数据
   using (SqlConnection connection = new SqlConnection("Data Source=AFOD3-609221015;Initial Catalog=MyData;Integrated Security=True"))
   {

   connection.Open();
   SqlCommand cmd = new SqlCommand();
   cmd.Connection = connection;

   string mandText = "Insert into Images values (@image, @Rollno,@img,getdate())";

   cmd.CommandText = mandText;
   cmd.CommandType = CommandType.Text;

   cmd.Parameters.Add("@image", SqlDbType.VarBinary);
   cmd.Parameters["@image"].Value = imagetype;

   cmd.Parameters.Add("@Rollno", SqlDbType.VarChar);
   cmd.Parameters["@Rollno"].Value = txtrollno.Text;

   cmd.Parameters.Add("@img", SqlDbType.VarChar);
   cmd.Parameters["@img"].Value = txtrollno.Text;


   cmd.ExecuteNonQuery();
   cmd.Dispose();
   connection.Close();

   Response.Write("导入成功");
   }
  }
  else
  {
   Response.Write("导入失败"); return;
  }
  }

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

protected void Button1_Click(object sender, EventArgs e)
 {
 string sConn = ConfigurationManager.AppSettings["ConnectionString"];

 SqlConnection objConn = new SqlConnection(sConn);
 
 objConn.Open();

 string sql = "select  from Images";

 SqlCommand cmd = new SqlCommand(sql, objConn);
 
 SqlDataReader dr = cmd.ExecuteReader();

 while (dr.Read())

 {

  byte[] bytes = (byte[])dr["img"];

  FileStream fs = new FileStream(@"E:\Images\" + dr["roll_no"] + ".jpg" , FileMode.Create, FileAess.Write);

  fs.Write(bytes, 0, bytes.Length);

  fs.Flush();

  fs.Close();

 }

 dr.Close();

 objConn.Close();
 
 Response.Write("成功导出"); 


 }