C#

public class BaseRef
{
    public int id {get; set;}
    public string listID {get; set;}
    public string Name {get; set;}
}

this.Columns.Add(new DataColumn("ParentRef", typeof(BaseRef)));

SELECT id, listID, Name FROM ParentTable

mapping.ColumnMappings.Add("id", "ParentRef.id");
mapping.ColumnMappings.Add("listID", "ParentRef.listID");
mapping.ColumnMappings.Add("Name", "ParentRef.Name");

public partial class FileWatcherEntities : DbContext
{
    public FileWatcherEntities()
        : base(WatcherDB.GetConnectionStringForEnvironment()) //("name=FileWatcherEntities")
    {
    }

    public virtual DbSet<DtsConnection> DtsConnections { get; set; }
    public virtual DbSet<DtsVariable> DtsVariables { get; set; }
    public virtual DbSet<ErrorLog> ErrorLogs { get; set; }
    public virtual DbSet<FileWatcherLog> FileWatcherLogs { get; set; }
    public virtual DbSet<ImportedDBDetails_NotUsed> ImportedDBDetails_NotUsed { get; set; }
    public virtual DbSet<ImportedSourceDetail> ImportedSourceDetails { get; set; }
    public virtual DbSet<PDFBlob> PDFBlobs { get; set; }
    public virtual DbSet<PriorityLookup> PriorityLookups { get; set; }
    public virtual DbSet<SSIS_Configuration> SSIS_Configurations { get; set; }
    public virtual DbSet<ImportMetaData> ImportMetaDatas { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<ErrorLog>()
            .Property(e => e.ApplicationName)
            .IsUnicode(false);

        modelBuilder.Entity<ErrorLog>()
            .Property(e => e.Version)
            .IsUnicode(false);

        modelBuilder.Entity<ErrorLog>()
            .Property(e => e.DateTS)
            .HasPrecision(2);

        modelBuilder.Entity<ErrorLog>()
            .Property(e => e.AppUsername)
            .IsUnicode(false);

        modelBuilder.Entity<PDFBlob>()
            .Property(e => e.FileName)
            .IsUnicode(false);

        ////base.OnModelCreating(modelBuilder);
        //modelBuilder.Entity<PDFBlob>().ToTable("etl.PDFBlob");
        //modelBuilder.Entity<PDFBlob>().HasKey(x => x.Id);

        var config = modelBuilder.Entity<PDFBlob>().ToTable("PDFBlob", schemaName: "etl");
        modelBuilder.Entity<PDFBlob>().HasKey(x => x.Id);
        //config.ToTable("etl.PDFBlob");
    }
}

[Table("PDFBlob", Schema = "etl")]
public partial class PDFBlob
{
    public long Id { get; set; }

    [Required]
    [StringLength(8000)]
    public string FileName { get; set; }

    [Required]
    public byte[] Content { get; set; }

    public long Size { get; set; }
}

private static long WritePdfFile(string path)
{
    var fInfo = new FileInfo(path);
    while (IsFileLocked(fInfo))
        Thread.Sleep(500);

    var byts = File.ReadAllBytes(path);

    using (var context = new FileWatcherEntities())
    {
        var blb = context.PDFBlobs.Add(new PDFBlob
        {
            Content = byts,
            FileName = Path.GetFileName(path),
            Size = byts.Length
        });

        context.SaveChanges();

        return blb.Id;
    }

    return 0;
}