Extract only certain columns from table and save it in text

Question

I am able to retrieve all the columns of values from a table using LINQ and display it. However, I only want to retrieve only certain columns (say column2 and column3) for display. How do I achieve that?

Also, I want to save those 2 columns of data in a text file, with no space and no separator between column2 and column3. How do I do it?

My code is as attached.

I would appreciate it very much for sample code.

thanks.

Vulpes · Answer

If all the code were in the same method you could extract a couple of columns using an anonymous type but you can't do that here because you're passing the query result to another method. I'd therefore suggest that you create a named 'helper' class to do this. Suppose for purposes of illustration that you want to extract columns called Id (a string) and Name (also a string) then you could do so as follows (off top of my head so watch out for bugs): using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; using System.IO; namespace Testing { /// /// Interaction logic for MainWindow.xaml /// public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void Output_button_Click(object sender RoutedEventArgs e) { string MoNo = MONO_TextBox.Text; dataGrid1.ItemsSource = ListTestID1234(MoNo); using (StreamWriter writer = new StreamWriter(somefile.txt)) { foreach(Helper h in dataGrid1.ItemsSource) { sw.WriteLine(String.Format({0}{1} h.Id h.Name)); } } } public static List ListTestID1234(string MoNo) // this data comes out almost instantly { using (TESTID1234Entities context = new TESTID1234Entities()) { int Mono = Convert.ToInt32(MoNo); var query = from products in context.TESTID1234 where products.MONO == Mono && products.SUB_TYPE4 == 126024 // not to be hardcoded. select new Helper{Id = products.Id Name = products.Name}; return query.ToList(); } } } public class Helper { public string Id {get; set;} public string Name {get; set;} } }

TAN WhoAMI · Answer

perfect code... thanks Vulpes. you are my Saviour :)