LINQ Pocket Reference

Query Operator Overview

The sections that follow describe each of the LINQ query operators, as summarized in Table 1-1.

Table 1-1. LINQ query operators

Category	Operators
Filtering	Where, Distinct, Take, TakeWhile, Skip, SkipWhile
Projecting	Select, SelectMany
Joining	Join, GroupJoin
Ordering	OrderBy, OrderByDescending, ThenBy, ThenByDescending, Reverse
Grouping	GroupBy
Set	Concat, Union, Intersect, Except
Conversion import)	OfType, Cast
Conversion export)	ToArray, ToList, ToDictionary, ToLookup, AsEnumerable, AsQueryable
Element	First, FirstOrDefault, Last, LastOrDefault, Single, SingleOrDefault, ElementAt, ElementAtOrDefault, DefaultIfEmpty
Aggregation	Aggregate, Average, Count, LongCount, Sum, Max, Min
Quantifiers	All, Any, Contains, SequenceEqual
Generation	Empty, Range, Repeat

The examples assume that a names array is defined as follows:

	string[] names = { "Tom","Dick","Harry","Mary","Jay" };

Examples that use LINQ to SQL assume a typed DataContext variable called dataContext:

	var dataContext = new DemoDataContext();

	...
	
	public class DemoDataContext : DataContext
	{
	  public DemoDataContext (string cxString)
	    : base (cxString) { }

	  public Table<Customer> Customers
	  { get { return GetTable<Customer>(); } }

	  public Table<Purchase> Purchases
	  { get { return GetTable<Purchase>(); } } 
	}

	[Table] public class Customer
	{
	  [Column(IsPrimaryKey=true)] public int ID;
	  [Column] public stringName;

	  [Association(OtherKey="CustomerID")]
	  public EntitySet<Purchase>Purchases = new EntitySet<Purchase>(); } ...