Extract only certain columns from table and save it in text

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.

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;}

}

2 Replies

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Vulpes13y ago
Accepted 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;}
}
}
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TAN WhoAMI13y ago
perfect code... thanks Vulpes. you are my Saviour :)
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