I have some doubts over how Enumerators work, and LINQ. Consider these two simple selects: List<Animal> sel = (from animal in Animals join race in Species on animal.SpeciesKey equals race.SpeciesKey select animal).Distinct().ToList(); or IEnumerable<Animal> sel = (from animal in Animals join race in Species on animal.SpeciesKey equals race.SpeciesKey select animal).Distinct(); I changed the names of … Read more
I’d like to do the equivalent of the following in LINQ, but I can’t figure out how: IEnumerable<Item> items = GetItems(); items.ForEach(i => i.DoStuff()); What is the real syntax? 22 s 22 There is no ForEach extension for IEnumerable; only for List<T>. So you could do items.ToList().ForEach(i => i.DoStuff()); Alternatively, write your own ForEach extension … Read more
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. Want to improve this question? Update the question so it’s on-topic for Stack Overflow. Closed 6 years ago. Improve this question What is Java equivalent for LINQ? 34 s 34
I’ve searched around and haven’t really found a clear answer as to when you’d want to use .First and when you’d want to use .FirstOrDefault with LINQ. When would you want to use .First? Only when you’d want to catch the exception if no results where returned? var result = List.Where(x => x == “foo”).First(); … Read more
I’m trying to perform a LINQ query on a DataTable object and bizarrely I am finding that performing such queries on DataTables is not straightforward. For example: var results = from myRow in myDataTable where results.Field(“RowNo”) == 1 select results; This is not allowed. How do I get something like this working? I’m amazed that … Read more
How can I do GroupBy multiple columns in LINQ Something similar to this in SQL: SELECT * FROM <TableName> GROUP BY <Column1>,<Column2> How can I convert this to LINQ: QuantityBreakdown ( MaterialID int, ProductID int, Quantity float ) INSERT INTO @QuantityBreakdown (MaterialID, ProductID, Quantity) SELECT MaterialID, ProductID, SUM(Quantity) FROM @Transactions GROUP BY MaterialID, ProductID 14 … Read more
What is the difference between returning IQueryable<T> vs. IEnumerable<T>, when should one be preferred over the other? IQueryable<Customer> custs = from c in db.Customers where c.City == “<City>” select c; IEnumerable<Customer> custs = from c in db.Customers where c.City == “<City>” select c; Will both be deferred execution and when should one be preferred over … Read more
Let’s suppose if we have a class like: class Person { internal int PersonID; internal string car; } I have a list of this class: List<Person> persons; And this list can have multiple instances with same PersonIDs, for example: persons[0] = new Person { PersonID = 1, car = “Ferrari” }; persons[1] = new Person … Read more
I’ve been searching the difference between Select and SelectMany but I haven’t been able to find a suitable answer. I need to learn the difference when using LINQ To SQL but all I’ve found are standard array examples. Can someone provide a LINQ To SQL example? 1 18
I am playing with LINQ to learn about it, but I can’t figure out how to use Distinct when I do not have a simple list (a simple list of integers is pretty easy to do, this is not the question). What I if want to use Distinct on a list of an Object on … Read more
