//获取当前选择的图片
this.pictureBox1.Image = Image.FromStream(this.openFileDialog1.OpenFile());
//获取当前图片的路径
string path = openFileDialog1.FileName.ToString();
//将制定路径的图片添加到FileStream类中    
FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
//通过FileStream对象实例化BinaryReader对象
BinaryReader br = new BinaryReader(fs);
//通过BinaryReader类对象的ReadBytes()方法将FileStream类对象转化为二进制数组
byte[] imgBytesIn = br.ReadBytes(Convert.ToInt32(fs.Length));

//将图片添加到数据库中
string sql="insert into pic values(@pic)"; 
SqlParameter[] param = new SqlParameter[] { new SqlParameter("@pic", imgBytesIn) };
DBHelper.GetExecuteQuery(sql, param);

//将图片从数据库中取出
string sql="select * from pic where id=0";
SqlDataReader reader = DBHelper.GetExecuteReader(sql, null);
MemoryStream mss = null;
if (reader.Read())
{
  byte[] bytes = (byte[])reader["pic"];
  mss = new MemoryStream(bytes);
}
this.pictureBox2.Image = Image.FromStream(mss);