SqlParameter 操作 image 字段

public static void AddEmployee(
  string lastName,
  string firstName,
  string title,
  DateTime hireDate,
  int reportsTo,
  string photoFilePath,
  string connectionString)
{
  byte[] photo = GetPhoto(photoFilePath);  

  using (SqlConnection connection = new SqlConnection(
    connectionString))  

  SqlCommand command = new SqlCommand(
    "INSERT INTO Employees (LastName, FirstName, " +
    "Title, HireDate, ReportsTo, Photo) " +
    "Values(@LastName, @FirstName, @Title, " +
    "@HireDate, @ReportsTo, @Photo)", connection);   

  command.Parameters.Add("@LastName",
     SqlDbType.NVarChar, ).Value = lastName;
  command.Parameters.Add("@FirstName",
      SqlDbType.NVarChar, ).Value = firstName;
  command.Parameters.Add("@Title",
      SqlDbType.NVarChar, ).Value = title;
  command.Parameters.Add("@HireDate",
       SqlDbType.DateTime).Value = hireDate;
  command.Parameters.Add("@ReportsTo",
      SqlDbType.Int).Value = reportsTo;  

  command.Parameters.Add("@Photo",
      SqlDbType.Image, photo.Length).Value = photo;  

  connection.Open();
  command.ExecuteNonQuery();
  }
}  

public static byte[] GetPhoto(string filePath)
{
  FileStream stream = new FileStream(
      filePath, FileMode.Open, FileAccess.Read);
  BinaryReader reader = new BinaryReader(stream);  

  byte[] photo = reader.ReadBytes((int)stream.Length);  

  reader.Close();
  stream.Close();  

  return photo;
}  

from: https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/sql/inserting-an-image-from-a-file