LINQ and C# 3.0LINQ and C# 3.0

Mads TorgersenMads TorgersenProgram Manager for the C# LanguageProgram Manager for the C# LanguageMicrosoft CorporationMicrosoft Corporation

fromfrom c c inin db.Customers db.Customerswherewhere c.City == “London” c.City == “London”select newselect new { c.Name, c.Address } { c.Name, c.Address }

LINQ ArchitectureLINQ Architecture

ObjectsObjects

<book> <title/> <author/> <price/></book>

XMLXMLRelationalRelational

LINQ enabled data sourcesLINQ enabled data sources

LINQ LINQ To ObjectsTo Objects

LINQ LINQ To XMLTo XML

LINQ enabled ADO.NETLINQ enabled ADO.NET

VBVB Others…Others…

LINQ LINQ To EntitiesTo Entities

LINQ LINQ To SQLTo SQL

LINQ LINQ To DatasetsTo Datasets

.Net Language Integrated Query (LINQ).Net Language Integrated Query (LINQ)

C#C#

C# 3.0 Language ExtensionsC# 3.0 Language Extensions

var contacts = from c in customers where c.State == "WA" select new { c.Name, c.Phone };

var contacts = customers .Where(c => c.State == "WA") .Select(c => new { c.Name, c.Phone });

Extension Extension methodsmethods

Lambda Lambda expressionsexpressions

Query Query expressionsexpressions

Object Object initializersinitializers

Anonymous Anonymous typestypes

Local Local variable type variable type

inferenceinference

Language Integrated QueryLanguage Integrated Query

Querying in Visual C# 3.0Querying in Visual C# 3.0

Extension methodsExtension methods – call static as – call static as instance instance

Lambda expressionsLambda expressions – inline methods – inline methods

Query expressionsQuery expressions – querying made – querying made simplesimple

Implicitly typed locals – Implicitly typed locals – save the save the typingtyping

Anonymous typesAnonymous types – temporary results – temporary results

Standard Query OperatorsStandard Query OperatorsRestrictRestrict s.s.WhereWhere(…)(…)

ProjectProject s.s.SelectSelect(…), s.(…), s.SelectManySelectMany(…)(…)

OrderOrder s.s.OrderByOrderBy(…).(…).ThenByThenBy(…) …(…) …

GroupGroup s.s.GroupByGroupBy(…)(…)

QuantifyQuantify s.s.AnyAny(…), s.(…), s.AllAll(…)(…)

PartitionPartition s.s.TakeFirstTakeFirst(…), s.(…), s.SkipFirstSkipFirst(…)(…)

SetSet s.s.DistinctDistinct(), s.(), s.UnionUnion(…), s.(…), s.IntersectIntersect(…), (…), s.s.ExceptExcept(…)(…)

SingletonSingleton s.s.ElementElement(…), s.(…), s.ElementAtElementAt(…)(…)

AggregatAggregatee

s.s.CountCount(), s.(), s.SumSum(), s.(), s.MinMin(), s.(), s.MaxMax(), (), s.s.AverageAverage(), s.(), s.AggregateAggregate()()

ConvertConvert s.s.ToArrayToArray(), s.(), s.ToListToList()()

CastCast s.s.OfTypeOfType<T>(), s.<T>(), s.CastCast<T><T>

DLinq for Relational DataDLinq for Relational Data

SqlConnection c = new SqlConnection(…);SqlConnection c = new SqlConnection(…);c.Open();c.Open();SqlCommand cmd = new SqlCommand(SqlCommand cmd = new SqlCommand( @"SELECT c.Name, c.Phone@"SELECT c.Name, c.Phone FROM Customers cFROM Customers c WHERE c.City = @p0");WHERE c.City = @p0");cmd.Parameters["@p0"] = "London";cmd.Parameters["@p0"] = "London";DataReader dr = c.Execute(cmd);DataReader dr = c.Execute(cmd);while (dr.Read()) {while (dr.Read()) { string name = r.GetString(0);string name = r.GetString(0); string phone = r.GetString(1);string phone = r.GetString(1); DateTime date = r.GetDateTime(2);DateTime date = r.GetDateTime(2);}}r.Close();r.Close();

Accessing data todayAccessing data today

Queries in Queries in quotesquotes

Loosely Loosely bound bound

argumentsarguments

Loosely Loosely typed result typed result

setssets

No compile No compile time checkstime checks

public class Customer { … }public class Customer { … }

public class Northwind: DataContextpublic class Northwind: DataContext{{ public Table<Customer> Customers;public Table<Customer> Customers; … …}}

Northwind db = new Northwind(…);Northwind db = new Northwind(…);var contacts =var contacts = from c in db.Customersfrom c in db.Customers where c.City == "London"where c.City == "London" select new { c.Name, c.Phone };select new { c.Name, c.Phone };

DLinq for Relational DataDLinq for Relational Data

Accessing data with DLinqAccessing data with DLinqClasses Classes

describe datadescribe data

Strongly Strongly typed typed

connectionconnection

Integrated Integrated query syntaxquery syntax

Strongly Strongly typed resultstyped results

Tables are Tables are like like

collectionscollections

XLinq for XML DataXLinq for XML Data

XmlDocument doc = new XmlDocument();XmlDocument doc = new XmlDocument();XmlElement contacts = doc.CreateElement("contacts");XmlElement contacts = doc.CreateElement("contacts");foreach (Customer c in customers)foreach (Customer c in customers) if (c.Country == "USA") {if (c.Country == "USA") { XmlElement e = doc.CreateElement("contact");XmlElement e = doc.CreateElement("contact"); XmlElement name = doc.CreateElement("name");XmlElement name = doc.CreateElement("name"); name.InnerText = c.CompanyName;name.InnerText = c.CompanyName; e.AppendChild(name);e.AppendChild(name); XmlElement phone = doc.CreateElement("phone");XmlElement phone = doc.CreateElement("phone"); phone.InnerText = c.Phone;phone.InnerText = c.Phone; e.AppendChild(phone);e.AppendChild(phone); contacts.AppendChild(e);contacts.AppendChild(e); }}doc.AppendChild(contacts);doc.AppendChild(contacts);

Programming XML todayProgramming XML today

<contacts><contacts> <contact><contact> <name>Great Lakes <name>Great Lakes Food</name>Food</name> <phone>(503) <phone>(503) 555-7123</phone>555-7123</phone> </contact></contact> … …</contacts></contacts>

Imperative Imperative modelmodel

Document Document centriccentric

No integrated No integrated queriesqueries

Memory Memory intensiveintensive

XLinq for XML DataXLinq for XML Data

XElement contacts = new XElement("contacts",XElement contacts = new XElement("contacts", from c in customersfrom c in customers where c.Country == "USA"where c.Country == "USA" select new XElement("contact",select new XElement("contact", new XElement("name", c.CompanyName),new XElement("name", c.CompanyName), new XElement("phone", c.Phone)new XElement("phone", c.Phone) ))););

Programming XML with XLinqProgramming XML with XLinqDeclarative Declarative

modelmodel

ElementElementcentriccentric

Integrated Integrated queriesqueries

Smaller and Smaller and fasterfaster

LINQ ExtensibilityLINQ Extensibility

New data sourcesNew data sourcesImplement the LINQ patternImplement the LINQ pattern

New languagesNew languagesUnified querying experienceUnified querying experience

Expression tree generationExpression tree generation

Unified call syntaxUnified call syntax

Query syntaxQuery syntax

Try it!Try it!

http://http://msdn.microsoft.com/netframework/future/limsdn.microsoft.com/netframework/future/linqnq

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