string sql
 = "update
 Table1 set name = 'Pudding' where ID = '1'";//未采用SqlParameter
SqlConnection
 conn = new SqlConnection();
conn.ConnectionString
 = "Data
 Source=.\\SQLExpress;Integrated Security=true;AttachDbFilename=|DataDirectory|\\Database.mdf;User Instance=true";//连接字符串与数据库有关
SqlCommand
 cmd = new SqlCommand(sql,
 conn);
try
{
  conn.Open();
  return(cmd.ExecuteNonQuery());
}
catch (Exception)
{
  return -1;
  throw;
}
finally
{
  conn.Close();
}

SqlParameter
 sp = new SqlParameter("@name","Pudding");
cmd.Parameters.Add(sp);
sp
 = new SqlParameter("@ID","1");
cmd.Parameters.Add(sp);

SqlParameter[]
 paras = new SqlParameter[]
 { new SqlParameter("@name","Pudding"),new SqlParameter("@ID","1")
 };
cmd.Parameters.AddRange(paras);

public int SavePhoto(string photourl)
{
  FileStream
 fs = new FileStream(photourl,
 FileMode.Open, FileAccess.Read);//创建FileStream对象，用于向BinaryReader写入字节数据流
  BinaryReader
 br = new BinaryReader(fs);//创建BinaryReader对象，用于写入下面的byte数组
  byte[]
 photo = br.ReadBytes((int)fs.Length);//新建byte数组，写入br中的数据
  br.Close();//记得要关闭br
  fs.Close();//还有fs
  string sql
 = "update
 Table1 set photo = @photo where ID = '0'";
  SqlConnection
 conn = new SqlConnection();
  conn.ConnectionString
 = "Data
 Source=.\\SQLExpress;Integrated Security=true;AttachDbFilename=|DataDirectory|\\Database.mdf;User Instance=true";
  SqlCommand
 cmd = new SqlCommand(sql,
 conn);
  SqlParameter
 sp = new SqlParameter("@photo",
 photo);
  cmd.Parameters.Add(sp);
  try
  {
    conn.Open();
    return (cmd.ExecuteNonQuery());
  }
  catch (Exception)
  {
    return -1;
    throw;
  }
  finally
  {
    conn.Close();
  }
}
 
public void ReadPhoto(string url)
  {
    string sql
 = "select
 photo from Table1 where ID = '0'";
    SqlConnection
 conn = new SqlConnection();
    conn.ConnectionString
 = "Data
 Source=.\\SQLExpress;Integrated Security=true;AttachDbFilename=|DataDirectory|\\Database.mdf;User Instance=true";
    SqlCommand
 cmd = new SqlCommand(sql,
 conn);
    try
    {
      conn.Open();
      SqlDataReader
 reader = cmd.ExecuteReader();//采用SqlDataReader的方法来读取数据
      if (reader.Read())
      {
        byte[]
 photo = reader[0] as byte[];//将第0列的数据写入byte数组
        FileStream
 fs = new FileStream(url,FileMode.CreateNew);创建FileStream对象，用于写入字节数据流
        fs.Write(photo,0,photo.Length);//将byte数组中的数据写入fs
        fs.Close();//关闭fs
      }
      reader.Close();//关闭reader
    }
    catch (Exception
 ex)
    {
      throw;
    }
    finally
    {
      conn.Close();
    }  }}