 Language Integrated Query  Make query a part of the language  Component of.NET Framework 3.5  Shipped with Visual Studio 2008

 Linq is short for L anguage In tegrated Q uery. If you are used to using SQL to query databases, you are going to have something of a head start with Linq, since they have many ideas in common.

 LINQ provides a high-level abstraction of virtually any data and emulates the query operations of the relational model.

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

 LINQ (often overheard pronounced as "link") is a step in the evolution of data access. It is a programming model that brings a much needed uniformity to accessing data from files, XML, database, registry, event log

 Allows to perform iterations on Collections  Main namespace is System.core

C# var myCustomers = from c in customers where c.Region == "UK" select c;

 Unified data access Single syntax to learn and remember  Strongly typed Catch errors during compilation  IntelliSense Prompt for syntax and attributes  Bindable result sets  More evident when more complex filters are present

OthersC#VB.NET.NET Language Integrated Query (LINQ) LINQ to SQL LINQ to Objects LINQ to XML LINQ to Datasets LINQ to Entities LINQ data source providers ADO.NET support for LINQ

 C# int[] nums = new int[] {0,4,2,6,3,8,3,1}; double average = nums.Take(6).Average(); var above = from n in nums where n > average select n;  Filtering process is easy because of the Intellisense feature

 Use of Ienumerable or Iqueryable collection  Query any IEnumerable source Includes arrays, List, Dictionary...  Instead of for each loops or iterative loops the condition of LINQ used along with Ienumerable helps in rapid data retrieval

AggregateConversionOrderingPartitioningSets Aggregate Average Count Max Min Sum Cast OfType ToArray ToDictionar y ToList ToLookup ToSequenc e OrderBy ThenBy Descending Reverse Skip SkipWhile Take TakeWhile Concat Distinct Except Intersect Union and many others

 LINQ to dataset is build on the top of ADO.Net to simplify the tasks  Ensure that a reference System.Data.DataSetExtensions.dll is added  Typed dataset feture is present(Fields)  Reshaping data with Anonymous type feature

 What is the Entity Data Model? Definition for your application model Map between app model, database schema Advanced mapping scenarios supported One entity mapped across multiple tables  Multiple inheritance hierarchy mappings  Many-to-many without "link" table in model

 LINQ to SQL Shipped with Visual Studio 2008 and.NET 3.5 Emphasis on rapid application development Supports Microsoft SQL Server family of databases  LINQ to Entities Will ship as an update to.NET 3.5 Offers a provider model for third-party databases Designed for enterprise-grade data scenarios Higher level of abstraction for programming databases Just one layer of the overall ADO.NET Entity Framework

 Converting LINQ queries to SQL Compiler converts code into a LINQ expression tree LINQ to Entities converts LINQ expression tree into a DbCommandTree based on mapping information  DbCommandTree expressed in terms of the database schema ADO.NET provider generates a DbCommand LINQ to Entities executes the DbCommand, assembles results into the structure(s) specified in the LINQ query

 EntityClient Provider string "SELECT VALUE o FROM NorthwindEntities.Orders AS o " + "WHERE o.Customers.CustomerID = 'ALFKI'"; EntityCommand new EntityCommand(eS EntityDataReader = while ( Console. ("{0} {1:d}", ["OrderID"], ["OrderDate"]);

 Object-relational mapping Records become strongly-typed objects  Data context is the controller mechanism  Facilitates update, delete & insert  Translates LINQ queries behind the scenes  Type, parameter and injection safe

 Instead of manipulating the database directly,developers manipulate the object model,which represents the database  For this,Windows application must be created  Add new LINQ to SQL class items to the project  Drag and drop tables and make changes.It will be saved only in the object model  To save changes in the database use the following syntax  Database.Submitchanges();

 VS 2008 designer or SQLMetal command  Map tables & fields to classes & properties  Generates partial classes with attributes  Each record becomes an object  Data context represents the database  Utilise tables, views or stored procedures

 Update Set object properties  Delete context.Table.DeleteOnSubmit(object)  Insert context.Table.InsertOnSubmit(object)  Commit changes back context.SubmitChanges() Transactional - all or nothing

 Debugging(Complex dedug in SP)  Deployment(.dll)  Type Safety (Errors)

 Extend functionality to an existing class without needing to subclass it  To add extension methods to objects implementing the Ienumerable interface,you need a reference to system.core.dll

Earlier Xpath or Xquery were used to manipulate XML documents, at present LINQ to XML concepts are used Add a reference to the System.xml.linq.dll in the project and also import System.xml.linq namespace Tree -> Xdocument ->XElement ->XAttribute LOAD XDocument LibraryBooks = new Xdocument(); LibraryBooks = Xdocument.load(“Books.xml”);

 Blinq Scaffold web UI for list/view/update pages  PLINQ Parallel query processing over many CPUs  SyncLINQ & Continuous LINQ Updated results via INotifyCollectionChanged

 PLINQ  Microsoft, as a part of the Parallel Extensions, is developing PLINQ, or Parallel LINQ, a parallel execution engine for LINQ queries. It defines the IParallelEnumerable interface. If the source collection implements this interface, the parallel execution engine is invoked. The PLINQ engine executes a query in a distributed manner on a multi-core or multi-processor system. [28]Parallel Extensions paralleldistributed [28]

.NET Framework 3.5  Anonymous types (shaping)  Extension methods (query operators)  Type inference (var keyword)  Lambda expressions (query syntax)