How to read and open files from a byte column in SQL Server?

Question

My question is the continuation of this question: Link to the other question

I managed to transform my file into bytes and insert it into a table in SQL Server, but now I want it from inside an application I am doing in C# I want to open this file. That is to do reverse engineering (byte > open file).

The code used for insertion:

Anexo a = new Anexo();
FileStream fs = new FileStream(a.Caminho, FileMode.Open, FileAccess.Read);
a.Arquivo = new byte[fs.Length];
fs.Read(a.Arquivo, 0, System.Convert.ToInt32(fs.Length));
string SQL = @"INSERT INTO ANEXO (NOME, CAMINHO, ARQUIVO) VALUES (@nome, @caminho, @arquivo)";
Cmd = new SqlCommand(SQL, Con);
Cmd.Parameters.Add("@nome", SqlDbType.VarChar).Value = a.NomeArquivo;
Cmd.Parameters.Add("@caminho", SqlDbType.VarChar).Value = a.Caminho;
Cmd.Parameters.Add("@arquivo", SqlDbType.VarBinary).Value = a.Arquivo;
Cmd.ExecuteNonQuery();

Answer 1

1. Get the byte array and pass to one MemoryStream in the builder;

2. Create your FileStream with the desired file name. I assume you are saving at least the original file extension (the name is optional, but if you mix different files, it is worth saving a column with the ". eml", ". txt", etc);

3. Read the bytes of MemoryStream and save in FileStream;

4. If you are going to open the file, you can call the Process.Start.

// aqui está seu array de bytes
byte[] arquivo;
const int BufferSize = 65536;

// create memory stream
using (var mstrm = new MemoryStream(arquivo))
{
    using (var outStream = File.Create("resultado.eml"))
    {
        var buffer = new byte[BufferSize];
        int bytesLidos;
        while ((bytesLidos = mstrm.Read(buffer, 0, BufferSize)) != 0)
        {
            outStream.Write(buffer, 0, bytesLidos);
        }
    }
}

Editing

Use the following code to read the file in its byte array:

public byte[] FileToByteArray(string fileName)
{
    byte[] buff = null;
    FileStream fs = new FileStream(fileName, 
                               FileMode.Open, 
                               FileAccess.Read);
    BinaryReader br = new BinaryReader(fs);
    long numBytes = new FileInfo(fileName).Length;
    buff = br.ReadBytes((int) numBytes);
    return buff;
}

It ensures that you can read large files! I know your files should not be too large, but if they have large attachments they may give problem.

To record, if not working, you can also use the way @Intruder pointed out as well:

File.WriteAllBytes(string caminho, byte[] array)

Answer 2

If your array represents a complete file:

File.WriteAllBytes(string path, byte[] bytes)