The “dot” notation is usually called Lambda syntax. The first notation goes by a number of names but I usually call it the query syntax. I work on a team of 10 developers and we argue at length about which we should use as a standard. In general, the more seasoned (with LINQ) developers migrate … Read more
You should definitely use ThenBy rather than multiple OrderBy calls. I would suggest this: tmp = invoices.InvoiceCollection .OrderBy(o => o.InvoiceOwner.LastName) .ThenBy(o => o.InvoiceOwner.FirstName) .ThenBy(o => o.InvoiceID); Note how you can use the same name each time. This is also equivalent to: tmp = from o in invoices.InvoiceCollection orderby o.InvoiceOwner.LastName, o.InvoiceOwner.FirstName, o.InvoiceID select o; If you … Read more
First, you’ll access the current grouped value as Key in your Select clause: .Select(“new (Key as Group, Sum(Value) as TotalValue)”); That should make your query work. The harder question is how to turn the returned objects, which will have a dynamically generated type that inherits from DynamicClass, into a static type. Option 1: Use reflection … Read more
If you are using EFv4 + EDMX you can create custom model defined function which will do the CAST for you. You can then use that function in Linq-to-entities queries.
You can do this, even across servers, as long as you can access one database from the other. That is, if it’s possible to write a SQL statement against ServerA.DatabaseA that accesses ServerB.DatabaseB.schema.TableWhatever, then you can do the same thing in LINQ. To do it, you’ll need to edit the .dbml file by hand. You … Read more
LINQ doesn’t really “do” recursion nicely. Your solution seems appropriate – although I’m not sure HasChildren is really required… why not just use an empty list for an item with no children? An alternative is to write a DescendantsAndSelf method which will return all of the descendants (including the item itself), something like this; // … Read more
You can always attach something to the .Log property of your DataContext. That will show all the SQL commands as they are sent. I do this in my base for data access objects and output it to the Visual Studio debug console. As the objects create their DataContext I check it see if its debug … Read more
You can always attach something to the .Log property of your DataContext. That will show all the SQL commands as they are sent. I do this in my base for data access objects and output it to the Visual Studio debug console. As the objects create their DataContext I check it see if its debug … Read more
If you express it as a where clause it may just work out of the box with LINQ to SQL, if you can construct an appropriate expression. There may be a better way of doing this in terms of the expression trees – Marc Gravell may well be able to improve it – but it’s … Read more
Use the following extension method to break the input into subsets public static class IEnumerableExtensions { public static IEnumerable<List<T>> InSetsOf<T>(this IEnumerable<T> source, int max) { List<T> toReturn = new List<T>(max); foreach(var item in source) { toReturn.Add(item); if (toReturn.Count == max) { yield return toReturn; toReturn = new List<T>(max); } } if (toReturn.Any()) { yield return … Read more