Paging a collection with LINQ

Question: How do you page through a collection in LINQ given that you have a startIndex and a count?

Solution:  Following natural way of paginating a LINQ collection.

var query = from i in ideas
            select i;
var pagedCollection = query.InPagesOf(10);
var pageOfIdeas = pagedCollection.Page(2);

How do I get a distinct, ordered list of names from a DataTable using LINQ?

Question: I have a DataTable with a Name column. I want to have a collection of the unique names ordered alphabetically. The following query ignores the order by clause.

var names =
    (from DataRow dr in dataTable.Rows
    orderby (string)dr["Name"]
    select (string)dr["Name"]).Distinct();

Why does the orderby not get enforced?

Solution:  To make it more readable and maintainable, you can also split it up into multiple LINQ statements.

1. First, select your data into a new list, let's call it x1, do a projection if desired
2. Next, create a distinct list, from x1 into x2, using whatever distinction you require
3. Finally, create an ordered list, from x2 into x3, sorting by whatever you desire

Filling a DataSet or DataTable from a LINQ query result set

Question: How do you expose a LINQ query as an ASMX web service? Usually, from the business tier, I can return a typed DataSet or DataTable which can be serialized for transport over ASMX.

public static MyDataTable CallMySproc()
{
    string conn = "...";

    MyDatabaseDataContext db = new MyDatabaseDataContext(conn);
    MyDataTable dt = new MyDataTable();

    // execute a sproc via LINQ
    var query = from dr
                in db.MySproc().AsEnumerable
                select dr;

    // copy LINQ query resultset into a DataTable -this does not work !    
    dt = query.CopyToDataTable();

    return dt;
}

How can I do the same for a LINQ query? Is there a way to populate a typed DataSet or DataTable via a LINQ query?

Solution: 

As mentioned in the question, IEnumerable has a CopyToDataTable method:

IEnumerable<DataRow> query =
    from order in orders.AsEnumerable()
    where order.Field<DateTime>("OrderDate") > new DateTime(2001, 8, 1)
    select order;

// Create a table from the query.
DataTable boundTable = query.CopyToDataTable<DataRow>();

Note: To everyone wondering why CopyToDataTable() doesn't work on their machine: This function is not part of .NET 3.5 SP1 nor will it be of .NET 4.0 and onwards.