using System;

using System.Xml;

using System.Xml.Linq;

using System.Linq;

public class Program

{

    public static void Main()

    {

        string xml = @"<Bookstore HasToys=""YES""> 

            <Authors>7</Authors>

            <Location>Austin TX</Location>

            <Employees>15</Employees>

            <ToyList>

                <ToyId>124</ToyId>

                <ToyId>1251</ToyId>

            </ToyList>

            <ToyList>

                <ToyId>255-2</ToyId>

                <ToyId>6623</ToyId>

            </ToyList>

        </Bookstore>";

        XDocument doc = XDocument.Parse(xml);

​

        var list = (from r in doc.Descendants("Bookstore")

                      .Where(node => (string)node.Attribute("HasToys") == "YES")

                        .Descendants("ToyList")

                        .Elements("ToyId")

                      select new

                      {

                            ToyId = r.Value,

                      });

        Console.WriteLine(String.Join(",", list.Select(x => x.ToyId)));

    }

}