Saturday, April 21, 2007

ORDER BY 1 Will Not Work In LINQ The Same As In SQL

I installed Visual Studio Orcas Beta 1 last night and now I am playing around with LINQ

You know how you can do the following in SQL

SELECT *
FROM SomeTable
ORDER BY 1

This will order the resultset by the first column. This of course is not good practice but that is not the point here. In LINQ if you do orderby 1 (that is right no space between order and by) it looks like that line is skipped, no error or exception is thrown

Dump the following code in a C# console application and try for yourself
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] names = { "Burke", "Connor", "Frank",
                       "Everett", "Albert", "George",
                       "Harris", "David" };

            IEnumerable expr = from s in names
                                       where s.Length == 6
                                       orderby 1
                                       //order by s
                                       select s.ToUpper();

            foreach (string item in expr)
                Console.WriteLine(item);
                Console.ReadLine();

        }


    }
}
at

2 comments:

  1. zproxy12:46 AM

    This i believe is by design. yea are sorting by the value 1 which in turn does not sort anything as each item sortable value is 1.

    Instead what you should do would look something like this:

    var r =
    from u in stuff
    select u
    orderby u.GetType().GetFields()[1].GetValue(u);

    ReplyDelete
  2. Anonymous11:15 AM

    "order by 1" used the way you describe is just sorting by the first column and assuming that it's an auto-incremented id. The right way would be to simply sort on that column by name.

    ReplyDelete