Questions tagged [linq]
Language Integrated Query (LINQ) is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages. Please consider using more detailed tags when appropriate, for example [linq-to-sql], [linq-to-entities] / [entity-framework], or [plinq]
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Multiple "order by" in LINQ
I have two tables, movies and categories, and I want to get an ordered list by categoryID first and then by Name.
The movie table has three columns ID, Name and CategoryID.
The category table has two ...
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votes
23
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LINQ's Distinct() on a particular property
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 ...
- 140k
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votes
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Difference Between Select and SelectMany
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 ...
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Group by in LINQ
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 ...
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votes
14
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Returning IEnumerable<T> vs. IQueryable<T>
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....
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15
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Group By Multiple Columns
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:
...
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LINQ query on a DataTable
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 ...
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When to use .First and when to use .FirstOrDefault with LINQ?
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'...
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883
votes
22
answers
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LINQ equivalent of foreach for IEnumerable<T>
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?
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866
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IEnumerable vs List - What to Use? How do they work?
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
...
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853
votes
12
answers
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LINQ Aggregate algorithm explained
This might sound lame, but I have not been able to find a really good explanation of Aggregate.
Good means short, descriptive, comprehensive with a small and clear example.
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14
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Using LINQ to remove elements from a List<T>
Say that I have LINQ query such as:
var authors = from x in authorsList
where x.firstname == "Bob"
select x;
Given that authorsList is of type List<Author>, how can ...
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754
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24
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Dynamic LINQ OrderBy on IEnumerable<T> / IQueryable<T>
I found an example in the VS2008 Examples for Dynamic LINQ that allows you to use a SQL-like string (e.g. OrderBy("Name, Age DESC")) for ordering. Unfortunately, the method included only ...
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Use LINQ to get items in one List<>, that are not in another List<>
I would assume there's a simple LINQ query to do this, I'm just not exactly sure how.
Given this piece of code:
class Program
{
static void Main(string[] args)
{
List<Person> ...
- 12.8k