C#

try
            {
                
                
                using (var db = new mombooksDataContext(Properties.Settings.Default.BooksConnectionString2))
                {
                    
                    
                                                                  
                                          
                    String[] splitstring = null;
                    string treeviewtext = treeView1.SelectedNode.Text;
                    splitstring = treeviewtext.Split(',');
                    var query = db.Books.SelectMany(o => o.BookAuthors.Where(a => a.Author.AuthorFirst == splitstring[1].ToString()));

                    bookBindingSource.DataSource = query.ToList();


                  
                    
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }

 1.
    String[] splitstring = null;
 2.
                        string treeviewtext = treeView1.SelectedNode.Text.Trim();
 3.
                        splitstring = treeviewtext.Split(',');
 4.

 5.
                        var query = from b in db.Books
 6.
                                    join ba in db.BookAuthors on b.ID equals ba.BookID
 7.
                                    join a in db.Authors on ba.AuthorID equals a.ID
 8.
                                    join bn in db.BookNumbers on ba.BookID equals bn.BookID
 9.
                                    where a.AuthorFirst ==splitstring[1].tostring()
10.
                                    select b;

using (GZipStream stream = new GZipStream(outfile, CompressionMode.Compress))

using (GZipStream stream = new GZipStream(outfile,"myfileName.xml", CompressionMode.Compress))