LINQ Basics

LINQ (Language Integrated Query, pronounced "link") is a Microsoft .NET Framework component that adds native data querying.)

Linq is the Microsoft's first attempt to integrate queries into language. We know, it is really easy to find data from sql objects simply writing a query while its somewhat hectic when we want to do the same thing in a DataTable or Lists. Generally we will have to loop through every elements to find the exact match, if there is some aggregation we need to aggregate the values etc. Linq provides an easy way to write queries that can run with the in memory objects.

Linq provides an easy way to write queries that can run with the in memory objects.

Example: (from item in itemlist where item.value = somevalue select item).toList();

Types of LINQ

Linq comes with 3 basic types (Provided there are lots of more types of LINQ on different type of objects :

1. LINQ (Linq to Objects)

   Linq To Objects - examine System.Linq.Enumerable for query methods. These target IEnumerable, allowing any typed loopable collection to be queried in a type-safe manner. These queries rely on compiled .Net methods, not Expressions.

2. DLINQ (Linq to SQL)
3. XLINQ (Linq to XML)

LINQ Operators

• Restriction Operator
  Where
• Projection Operator
  Select
• Partition Operators
  Take, Skip, TakeWhile, SkipWhile
• Ordering Operators
  OrderBy, OrderByDescending, ThenBy, ThenByDescending, Reverse
• Grouping Operators
  GroupBy
• Set Operators
  Distinct, Union, Intersect, Except
• Conversion Operators
  ToArray, ToList, ToDictionary, OfType
• Element Operators
  First, FirstOrDefault, ElementAt
• Generation Operators
  Range, Repeat
• Quantifiers
  Any, All
• Aggregate Operators
  Count, Sum, Min, Max, Average, Aggregate
• Miscellaneous Operators
  Concat, EquallAll
• Custom Sequence Operators
  Combine
• Query Execution
  Deferred, Immediate, Query Reuse
• Join Operators
  Cross Join, Group Join, Cross Join with Group Join, Left Ounter join

101 LINQ Samples
http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b

LINQ to Objects

http://www.codeproject.com/KB/dotnet/LINQ.aspx

http://www.codeproject.com/KB/cs/InsideAnonymousMethods.aspx

What is Language-Integrated Query - LINQ?

LINQ Query Expressions