How to retrieval of binary data from bytea data type in postgres

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C#

WinForms

PostgreSQL

We have data in serialized form of binary.Now we have to store it in PostGre database.
For insertion , we had stored the code in data column of bytea .
And use the following code:

using (FileStream pgFileStream = new FileStream("F:\\Test.abc", FileMode.Open, FileAccess.Read))
            {
                using (BinaryReader pgReader = new BinaryReader(new BufferedStream(pgFileStream)))
                {

                    NpgsqlCommand command = new NpgsqlCommand();

                    byte[] ByteA = pgReader.ReadBytes(Convert.ToInt32(pgFileStream.Length));
                    command.CommandText = "insert into ptadata (memberid, filedata) VALUES (03, @data)";
                    command.Connection = m_IDBcloudConnection;

                    //m_IDBcloudConnection.Close();
                    if (m_IDBcloudConnection.State != ConnectionState.Open)
                    {
                        m_IDBcloudConnection.Open();
                    }                    
                    command.Parameters.Add("@data", ByteA).Value = ByteA;

                    command.ExecuteNonQuery();

                    m_IDBcloudConnection.Close();
                }
            }

But when we try to retrieve it ,comes in the form of byte.
How can I get the data in serialized form of binary?

What I have tried:

using (FileStream pgFileStream = new FileStream("F:\\Test.abc", FileMode.Open, FileAccess.Read))
            {
                using (BinaryReader pgReader = new BinaryReader(new BufferedStream(pgFileStream)))
                {

                    NpgsqlCommand command = new NpgsqlCommand();

                    byte[] ByteA = pgReader.ReadBytes(Convert.ToInt32(pgFileStream.Length));
                    command.CommandText = "insert into ptadata (memberid, filedata) VALUES (03, @data)";
                    command.Connection = m_IDBcloudConnection;

                    //m_IDBcloudConnection.Close();
                    if (m_IDBcloudConnection.State != ConnectionState.Open)
                    {
                        m_IDBcloudConnection.Open();
                    }                    
                    command.Parameters.Add("@data", ByteA).Value = ByteA;

                    command.ExecuteNonQuery();

                    m_IDBcloudConnection.Close();
                }
            }