从数据库下载pdf文件时更改的文件名

我将PDF文件保存在数据库中，从数据库下载后，我看到它的名称完全更改为类似代码的内容，您能解释一下为什么吗？ 以及如何解决此问题以获取与PDF文件相同的名称？ 这是代码：

插入

OpenFileDialog ofd = new OpenFileDialog();
        ofd.ShowDialog();
        byte[] file;
        using (var stream = new FileStream(ofd.FileName, FileMode.Open, FileAccess.Read))
        {
            using (var reader = new BinaryReader(stream))
            {
                file = reader.ReadBytes((int)stream.Length);
            }
        }
        SqlConnection varConnection = new SqlConnection("Server=.''sqlexpress;Database=badge;integrated security=yes");
        varConnection.Open();
        using (var sqlWrite = new SqlCommand("INSERT INTO archive Values(@dat,@disponible,@fil)", varConnection))
        {
            sqlWrite.Parameters.Add("@dat", SqlDbType.Date).Value = DateTime.Today;
            sqlWrite.Parameters.Add("@disponible", SqlDbType.VarChar, 20).Value = comboBox1.Text;
            sqlWrite.Parameters.Add("@fil", SqlDbType.VarBinary, file.Length).Value = file;
            sqlWrite.ExecuteNonQuery();
        }
        varConnection.Close();
OpenFileDialog ofd = new OpenFileDialog();
        ofd.ShowDialog();
        byte[] file;
        using (var stream = new FileStream(ofd.FileName, FileMode.Open, FileAccess.Read))
        {
            using (var reader = new BinaryReader(stream))
            {
                file = reader.ReadBytes((int)stream.Length);
            }
        }
        SqlConnection varConnection = new SqlConnection("Server=.''sqlexpress;Database=badge;integrated security=yes");
        varConnection.Open();
        using (var sqlWrite = new SqlCommand("INSERT INTO archive Values(@dat,@disponible,@fil)", varConnection))
        {
            sqlWrite.Parameters.Add("@dat", SqlDbType.Date).Value = DateTime.Today;
            sqlWrite.Parameters.Add("@disponible", SqlDbType.VarChar, 20).Value = comboBox1.Text;
            sqlWrite.Parameters.Add("@fil", SqlDbType.VarBinary, file.Length).Value = file;
            sqlWrite.ExecuteNonQuery();
        }
        varConnection.Close();

下载：

SqlConnection varConnection = new SqlConnection("Server=.''sqlexpress;Database=badge;integrated security=yes");
        SqlCommand cmd = new SqlCommand();
        cmd.CommandText = "select fil from archive where dat = '" + dateTimePicker1.Value.ToString("yyyy-MM-dd") + "' and disponible='"+comboBox1.Text+"'";
        cmd.Connection = varConnection;
        varConnection.Open();
        SqlDataReader sqlRead = cmd.ExecuteReader();
        SaveFileDialog svd = new SaveFileDialog();
        svd.ShowDialog();
        if (sqlRead.HasRows)
        {
            while (sqlRead.Read())
            {
                byte[] fileData = (byte[])sqlRead[0];
                BinaryWriter fileCreate =
                    new BinaryWriter(File.Open(svd.FileName, FileMode.Create));
                fileCreate.Write(fileData);
                fileCreate.Close();
            }
        }
        varConnection.Close();

SaveFileDialog svd = new SaveFileDialog();
// ...
// svd.FileName is used, that is, user provided file name for the saved file
BinaryWriter fileCreate =  new BinaryWriter(File.Open(svd.FileName, FileMode.Create));