在数据库中保存文件

以下程序不完整，仅供需要时参考

保存图片：

OleDbConnection mycnn=new OleDbConnection("provider=Microsoft.jet.oledb.4.0;data source=f:\\dazhu.mdb");
mycnn.Open();

OleDbCommand mycmd=new OleDbCommand("update info set picture=@a",mycnn );

FileStream mystream=new FileStream("f:\\1.jpg",FileMode.Open,FileAccess.Read);
long len=mystream.Length;

mycmd.Parameters.Add("@a",OleDbType.Binary,(int)len,"picture");
mycmd.Parameters["@a"].Direction=System.Data.ParameterDirection.Input;

byte []box=new byte[len];
mystream.Read(box,0,(int)len);

mycmd.Parameters["@a"].Value=box;

//更新
mycmd.ExecuteNonQuery();
MessageBox.Show("ok");
mystream.Close();
mycnn.Close();


读取图片：
OleDbConnection mycnn=new OleDbConnection("provider=Microsoft.jet.oledb.4.0;data source=f:\\dazhu.mdb");
mycnn.Open();
MessageBox.Show("ok.mycnn.open");
OleDbCommand mycmd=new OleDbCommand("select * from info",mycnn );
OleDbDataReader myrd=mycmd.ExecuteReader();
if(myrd.Read())
{
//读取图片
byte []box=(byte [])myrd["picture"];

//构造流

Stream stream1=new MemoryStream(box);
this.pictureBox2.Image=System.Drawing.Image.FromStream(stream1);

//判断文件是否存在
//if(File.Exists("f:\\lingshi.jpg"))
//{//删除
//File.Delete("f:\\lingshi.jpg");

//}
stream1.Close();

}