reading or converting to file -byte[] array wrong

my name Is Omer and I’m a student. In my project I had to upload videos to database and also read them from the database. I’m using OLE object field to store byte[]array. But IDK why I Cant convert it back to file. I don’t know if my problem is in the inserting from the database or in the selecting. my Inserting code:

string username = RegisterFunctions.getUsername(Session["userInfo"]);
        string heroName = Hero.Text;
        VideoService vid = new VideoService();
        string path = vid.SaveFileInFoder(myUpload.PostedFile, "potg", Server);
        byte[] videoBy = vid.ConvertFileToByte(path);
        vid.UploadVideo(heroName,username,videoBy);

SaveFileInFoder:

public  string SaveFileInFoder(HttpPostedFile file, string folder, HttpServerUtility Server)
    {
        string location;

        if (file != null && file.ContentLength > 0)
        {
            location = Server.MapPath(folder) + "\" + System.IO.Path.GetFileName(file.FileName);

            try
            {
                file.SaveAs(location);
            }
            catch (Exception ex)
            {
                location = ex.Message;
            }
        }
        else
        {
            location = null;
        }

        return location;
    }

UploadVideo:

public void UploadVideo(string hero, string username , byte[] file)
    {
        OleDbConnection conn = new OleDbConnection(Connect.GetConnectionString());
        conn.Open();
        try
        {
            string sql = "Insert Into videos(username, hero, file) Values('"+username+"','"+hero+"','"+file+"') ";
            OleDbCommand com = new OleDbCommand(sql, conn);
            com.ExecuteNonQuery();
            com.Dispose();
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            conn.Close();
        }
    }

the selecting part:

DataTable table = VideoService.SelectVideos();
        videoLength = table.Rows.Count.ToString();
        string path = Server.MapPath("/potg");
        System.IO.DirectoryInfo di = new DirectoryInfo(path);
        for (int i = 0; i < table.Rows.Count; i++)
        {
            videoList += "var video1 = new video('" + table.Rows[i]["hero"] + "'," 
                + table.Rows[i]["videoid"] + ",'" + table.Rows[i]["username"] + "','" +
                table.Rows[i]["rating"] + "');" + "videos[" + i + "] = video1;";

            File.WriteAllBytes(path + "\" + table.Rows[i]["videoid"] + ".mp4", (byte[])table.Rows[i]["file"]);
        
        }

Answer

For the sake of simplicity I am saving file data as VarBinary(MAX) in the table. For big files ( bigger than ~1MB) you probably will use BLOB or FileStream.

File Stream Storage SQL 2008

Simple Get File method : (omitting validation and try ,catch)

public byte[] GetVideo(string movieName)
    {
        byte[] file;
        using (var stream = new FileStream(string.Format(@"C:UsersDataVideos{0}.mp4", movieName), FileMode.Open, FileAccess.Read))
        {
            using (var reader = new BinaryReader(stream))
            {
                file = reader.ReadBytes((int)stream.Length);
            }
        }

        return file;
    }

Save Data in DB (try avoiding using SQL reserved word for column names, like ‘file’)

    public void UploadVideo(string hero, string username, byte[] file)
    {
        // OleDbConnection implements IDisposable
        using (OleDbConnection conn = new OleDbConnection(Connect.GetConnectionString()))
        {

            conn.Open();

            // DbCommand implements IDisposable
            using (OleDbCommand cmd = conn.CreateCommand())
            {
                // command with placeholders in order to prevent sql injection
                // NOTE : OleDb does not support named parameters, so ? symbol is used here
                cmd.CommandText = "Insert Into videos ([username], [hero], [movieFile]) VALUES(?, ?, ?)";

                // add parameters
                cmd.Parameters.AddWithValue("@username", username);
                cmd.Parameters.AddWithValue("@hero", hero);
                cmd.Parameters.AddWithValue("@file", file);
                
                // execute
                cmd.ExecuteNonQuery();
            }
        }
    }

Get Data from DB and save as MP4 file

public void SaveVideos(string videoName)
    {
        DataTable table = VideoService.SelectVideos();
        string path =string.Format(@"C:UsersDataVideos{0}.mp4",videoName);
        for (int i = 0; i < table.Rows.Count; i++)
        {
            //...
            //...
            //...
            File.WriteAllBytes(path, (byte[])table.Rows[i]["movieFile"]);
        }
    }