Question

I had following Service method –

public static DataTable GetBookDetails(BookEntities context)
    {
        DataTable dtBooks= new DataTable();
        dtBooks.TableName = "BookDetails";
        dtBooks.Columns.Add(new DataColumn("Name",typeof(string)));
        dtBooks.Columns.Add(new DataColumn("ISBN",typeof(string)));
        dtBooks.Columns.Add(new DataColumn("Price",typeof(int)));
        dtBooks.Columns.Add(new DataColumn("Author",typeof(string)));
        IQueryable<Book> query = from b in context.Books.Include("Authors")
                                                                      .Include("Details/Price")
                                                                      .Include("Activity")
                                     where b.Activity.IsActive
                                     select b;
        if (query != null)
        {
            var sorted = query.ToArray().OrderByDescending(b => b.Activity.DateCreated);
            foreach (Book bb in sorted)
            {
                DataRow row = dtBooks.NewRow();
                row["Name"] = bb.Name;
                row["ISBN"] = bb.ISBN;
                row["Price"] = bb.Details.Price.CostOfBook;
                row["Author"] = bb.Authors.Name;
                dtBooks.Rows.Add(row);
            }
        }
        else
            dtBooks= null;
        return dtBooks;
    }

My Questions are –

1. Is this an efficient way to get details or can I improve this method?
2. Someone suggested me to use IList instead of DataTable. Should I use this? If so, what are the advantages?
3. What’s wrong in using DataTable?

Answer 1

DataTable vs IList

IList represent collection that can be accessed by index. Nothing more.

DataTable also has similar capabilities, but it provides much more functionality (like more events, More features) and is suitable where these features are required like representing Tabular data with advance capabilities (binding, custom sorting, grouping, event for row changed, cell added etc). All these extra features comes at extra overhead (of more memory requirement).

Is this the efficient way to get details or I can improve this method?

You can slightly improve by using IList. The improvement is not in faster data access, but in not using extra features that DataTable provides.If you dont require access by index, you can further improve by using IEnumerable.
You can further improve upon by using generics version. IList<T>, or IEnumerable<T> to save upon boxing/unboxing overhead.

Someone suggested me to use IList instead of DataTable. Should I use this? If so, what are the advantages?

IList does not have overhead of plethora of features provided by DataTable other than access by index.

Whats wrong in using DataTable?

Nothing wrong. DataTable is more suitable where advanced data access features are required.