Dev221 Dev221 VBVB中的中的LINQ:LINQ:未来之路未来之路

课程内容概述课程内容概述

LINQLINQ的字面含义是的字面含义是““语言集成的查询语言集成的查询””-- Language Language INtegratedINtegrated QueryQuery。它是下一版。它是下一版Visual StudioVisual Studio的功的功能重点之一。它扩展了能重点之一。它扩展了VBVB，让大家可以使用类似，让大家可以使用类似SQLSQL的语言来操作多个数据源，例如的语言来操作多个数据源，例如Object Object Collection, XML, DatasetCollection, XML, Dataset以及以及DatabaseDatabase。。

课程内容安排课程内容安排

LINQLINQ项目概述项目概述

基于对象数据的基于对象数据的LINQLINQ基于基于SQLSQL的的LINQ(DLinqLINQ(DLinq) ) 基于基于XMLXML的的LINQ(XLinqLINQ(XLinq) )

Visual Basic 9.0Visual Basic 9.0

简化查询数据简化查询数据在在VBVB语言中集成查询操作语言中集成查询操作

对对象数据、关系型数据和对对象数据、关系型数据和XMLXML数据建立统一的查询数据建立统一的查询

便于使用便于使用XMLXML快速生成快速生成XMLXML文档文档

简化性、一致性简化性、一致性&&提高生产效率提高生产效率

Language Integrated QueryLanguage Integrated Query

LINQLINQ项目项目

StandardStandardQueryQuery

OperatorsOperators

ObjectsObjects

DLinqDLinq(ADO.NET)(ADO.NET)

XLinqXLinq((System.XMLSystem.XML))

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

</book>

XMLXML

.NET Language Integrated Query.NET Language Integrated Query

VBVB C#C# OthersOthers……

SQLSQL

LINQLINQ的创新点的创新点

对对象数据、关系型数据和对对象数据、关系型数据和XMLXML数据建立统一的数据建立统一的查询和转换查询和转换

VBVB查询语法类似于查询语法类似于SQLSQL和和XqueryXquery

查询的类型检查、查询的类型检查、intellisenseintellisense和代码重构和代码重构

语言语言/API/API设计具有可扩展性设计具有可扩展性

语言的创新点语言的创新点

Implicitly typed localsImplicitly typed locals

隐式类型的局部变量隐式类型的局部变量

Extension methodsExtension methodsExtensionExtension方法方法

Inline functionsInline functions内联函数内联函数

Object Object initializersinitializers对象初始值对象初始值

Anonymous typesAnonymous types匿名类型匿名类型

Query expressionsQuery expressions查询表达式查询表达式

Dim x = 5Dim x = 5

<Extension><Extension>Sub Sub Randomize(colRandomize(col As Collection)As Collection)

Function(cFunction(c) ) c.Namec.Name

New Point { x := 1, y := 2 }New Point { x := 1, y := 2 }

New { New { c.Namec.Name, , c.Phonec.Phone }}

From From …… Where Where …… SelectSelect

查询语法查询语法

ProjectProject SelectSelect <<exprexpr>>

FilterFilter WhereWhere <<exprexpr>>

TestTest Any(Any(<<exprexpr>>)), , All(All(<<exprexpr>>))

JoinJoin <<exprexpr> > JoinJoin <<exprexpr> > OnOn <<exprexpr>>

GroupGroup GroupGroup ByBy <<exprexpr>>

AggregateAggregate Count(Count(<<exprexpr>>)), , Sum(Sum(<<exprexpr>>)), , Min(Min(<<exprexpr>>)), , Max(Max(<<exprexpr>>)), , AvgAvg((<<exprexpr>>))

PartitionPartition TopTop <<exprexpr>>

SetSet DistinctDistinct, , UnionUnion, , IntersectIntersect, , ExceptExcept

OrderOrder OrderOrder ByBy <<exprexpr>>

ConvertConvert ToArrayToArray,, ToListToList, , ToBindingListToBindingList

CastCast As As <<typenametypename>, >, OfType(OfOfType(Of T)T)

关系型数据的关系型数据的DLinqDLinq

SqlConnectionSqlConnection c = new c = new SqlConnectionSqlConnection((……););c.Openc.Open();();SqlCommandSqlCommand cmdcmd = new = new SqlCommandSqlCommand((@"SELECT @"SELECT c.Namec.Name, , c.Phonec.Phone

FROM Customers cFROM Customers cWHERE WHERE c.Cityc.City = @p0");= @p0");

cmd.Parameters["@p0"] = "London";cmd.Parameters["@p0"] = "London";DataReaderDataReader drdr = = c.Execute(cmdc.Execute(cmd););while (while (dr.Readdr.Read()) {()) {

string name = r.GetString(0);string name = r.GetString(0);string phone = r.GetString(1);string phone = r.GetString(1);DateTimeDateTime date = r.GetDateTime(2);date = r.GetDateTime(2);

}}r.Closer.Close();();

当前访问数据的方法当前访问数据的方法

Queries in Queries in quotesquotes

Loosely bound Loosely bound argumentsarguments

Loosely typed Loosely typed result setsresult sets

No compile No compile time checkstime checks

Public Class Customer Public Class Customer ……

Public Class NorthwindPublic Class NorthwindInherits DataContextInherits DataContext

Public Property Customers As Table(Of Customer)Public Property Customers As Table(Of Customer)……

End ClassEnd Class

Dim db As New Northwind(Dim db As New Northwind(……))Dim contacts = _ Dim contacts = _

From c in db.Customers _From c in db.Customers _Where c.City = "London"Where c.City = "London"Select c.Name, c.Phone Select c.Name, c.Phone

关系型数据的关系型数据的DLinq DLinq

使用使用DLingDLing访问数据访问数据

Classes Classes describe datadescribe data

Strongly typed Strongly typed connectionconnection

Integrated Integrated query syntaxquery syntax

Strongly typed Strongly typed resultsresults

Tables are like Tables are like collectionscollections

编写DLinq应用程序编写DLinq应用程序

关系型数据的关系型数据的DLinq DLinq

使用语言中的数据访问使用语言中的数据访问影射影射tables/rows tables/rows 到类到类//对象对象

基于基于ADO.NET ADO.NET 以及以及.NET Transactions.NET Transactions

影射影射

工具生成或手工编写工具生成或手工编写

其它其它

可以使用存储过程可以使用存储过程

支持其实数据库支持其实数据库 ((需插件需插件))

XMLXML数据的数据的XLinq XLinq

Dim doc As New XmlDocument()Dim doc As New XmlDocument()Dim contacts As XMLElement = doc.CreateElement("contacts")Dim contacts As XMLElement = doc.CreateElement("contacts")For Each Dim c in CustomersFor Each Dim c in Customers

If (c.Country = "USA") If (c.Country = "USA") Dim e As XMLElement = doc.CreateElement("contact")Dim e As XMLElement = doc.CreateElement("contact")Dim name As XMLElement = doc.CreateElement("name")Dim name As XMLElement = doc.CreateElement("name")name.InnerText = c.CompanyNamename.InnerText = c.CompanyNamee.AppendChild(name)e.AppendChild(name)Dim phone As XMLElement = doc.CreateElement("phone")Dim phone As XMLElement = doc.CreateElement("phone")phone.InnerText = c.Phonephone.InnerText = c.Phonee.AppendChild(phone)e.AppendChild(phone)contacts.AppendChild(e)contacts.AppendChild(e)

End IfEnd IfNextNextdoc.AppendChild(contacts)doc.AppendChild(contacts)

当前当前XMLXML编程方式编程方式

<contacts><contacts><contact><contact>

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

</contact></contact>……

</contacts></contacts>

Imperative Imperative modelmodel

Document Document centriccentric

No integrated No integrated queriesqueries

Memory Memory intensiveintensive

XMLXML数据的数据的XLinqXLinq

DimDim contacts contacts AsAs NeNew XElement("contacts",w XElement("contacts", __FFrom c in customersrom c in customers _ _ WWhere c.Country = "USAhere c.Country = "USA““ __SSelect elect NNew XElement("contact",ew XElement("contact", __

new XElement("name", c.CompanyName),new XElement("name", c.CompanyName), __new XElement("phone", c.Phone)new XElement("phone", c.Phone) __

))))

使用使用XLinqXLinq进行编程进行编程Declarative Declarative

modelmodel

ElementElementcentriccentric

Integrated Integrated queriesqueries

Smaller and Smaller and fasterfaster

在在Visual BasicVisual Basic中集成中集成XMLXML

Dim contacts = _Dim contacts = _<contacts><contacts><%=<%= __

From c In customers _From c In customers _Where c.Country = "USA" _Where c.Country = "USA" _Select <contact>Select <contact>

<name><name><%=<%= c.CompanyName c.CompanyName %>%></name></name><phone><phone><%=<%= c.Phone c.Phone %>%></phone></phone>

</contact> _</contact> _%>%>

</contacts></contacts>

利用利用XLinqXLinq在在VBVB中进行中进行XMLXML编程编程Infers XLinq Infers XLinq XElementXElement

No conceptual No conceptual barrierbarrier

Expression holes for Expression holes for computed values computed values

使用XLinq使用XLinq

XMLXML数据的数据的XLinqXLinq

与语言集成的与语言集成的XMLXML查询查询具有具有XPath / XQueryXPath / XQuery的表达能力的表达能力

将将VBVB或或C#C#作为编程语言作为编程语言XMLXML和代码之间无任何概念上的障碍和代码之间无任何概念上的障碍

利用利用DOMDOM的经验的经验元素为中心元素为中心,,而不是文档为中心而不是文档为中心

对称的元素对称的元素//属性属性APIAPI功能性的构造功能性的构造文本结点仅仅是字符串文本结点仅仅是字符串简化的简化的XMLXML命名空间支持命名空间支持更快且更小更快且更小

LINQLINQ项目项目

.NET.NET的的Language Integrated Query Language Integrated Query 在在VB9.0VB9.0和和C#3.0C#3.0的语言中具有内建的查询语法的语言中具有内建的查询语法

标准查询操作标准查询操作对任意对任意.NET.NET集合的类似集合的类似SQLSQL的查询的查询

DLinqDLinq可查询的数据访问框架可查询的数据访问框架

XLinqXLinq可查询的可查询的XML DOM, XML DOM, 并且更小并且更小, , 更快更快

总结总结

Language Integrated QueryLanguage Integrated Query LanguageLanguage 的优点的优点对于对象数据对于对象数据,,关系型数据和关系型数据和XMLXML数据的统一查询数据的统一查询查询的类型查询的类型在在VBVB和和C#C#中的类似中的类似SQLSQL和和XQueryXQuery的查询的查询仅支持仅支持.NET.NET平台平台

更多信息更多信息主页主页: : http://msdn.microsoft.com/netframework/future/linq/http://msdn.microsoft.com/netframework/future/linq/可下载可下载Customer Tech PreviewsCustomer Tech Previews版本版本!!

Contact: Juliapa@microsoft.comContact: Juliapa@microsoft.com

我们需要您的反馈意见我们需要您的反馈意见

© 2005 Microsoft Corporation. All rights reserved.This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.

XML Member BindingXML Member BindingXMLXML成员绑定成员绑定

Late binding covers all XML axesLate binding covers all XML axes延后绑定所有的延后绑定所有的XML axesXML axes

Dim cosmos As XElement = GetCurrentLinkCosmos().RootDim cosmos As XElement = GetCurrentLinkCosmos().RootDim ver As Double = CDbl(cosmos.Attribute("version"))Dim ver As Double = CDbl(cosmos.Attribute("version"))Dim item As XElement = First(cosmos.Descendents("item"))Dim item As XElement = First(cosmos.Descendents("item"))Dim created As Date = CDate(item.Element("linkcreatedDim created As Date = CDate(item.Element("linkcreated““))))

Dim cosmos As XElement = GetCurrentLinkCosmos().RootDim cosmos As XElement = GetCurrentLinkCosmos().RootDim ver As Double = CDbl(cosmos.@version)Dim ver As Double = CDbl(cosmos.@version)Dim item As XElement = cosmosDim item As XElement = cosmos……<item>.Value<item>.ValueDim created As Date = CDate(item.<linkcreated>)Dim created As Date = CDate(item.<linkcreated>)

AttributesAttributes

DescendentsDescendentsElementsElements

XML LiteralsXML LiteralsXML LiteralsXML Literals

Shorthand for object creationShorthand for object creation编写对象生成代码编写对象生成代码Dim emp = _Dim emp = _

<employee><employee><name>Joe</name><name>Joe</name><age>28</age><age>28</age><department id="432"><department id="432">

<deptname>Engineering</deptname><deptname>Engineering</deptname></department></department>

</employee></employee>

Dim emp = _Dim emp = _New XElement("employee", _New XElement("employee", _

New XElement("name", "Joe"), _New XElement("name", "Joe"), _New XElement("age", 28), _New XElement("age", 28), _New XElement("department", _New XElement("department", _

New XElement("name", "Engineering"), _New XElement("name", "Engineering"), _New XAttribute("id", 432)))New XAttribute("id", 432)))

Deferred Query ExecutionDeferred Query Execution向后优先解析的查询表达式向后优先解析的查询表达式Dim custs() As Customer = SampleData.GetCustomers()Dim custs() As Customer = SampleData.GetCustomers()

custscusts

PhonePhoneNameNameIDID

Dim q = Select c.City From c In custs Where c.State = "WA"Dim q = Select c.City From c In custs Where c.State = "WA"

Dim q = custs.Where(AddressOf _Filter1).Select(AddressOf _ProjecDim q = custs.Where(AddressOf _Filter1).Select(AddressOf _Project1)t1)

SelectSelect

AddressOf AddressOf _Project1_Project1

Dim names() As String = q.ToArray()Dim names() As String = q.ToArray()

namesnames

AddressOf _Filter1AddressOf _Filter1

WhereWhere

Expression TreesExpression Trees 表达式树表达式树

Defer code interpretationDefer code interpretation向后优先解析的代码向后优先解析的代码

Dim f As Predicate(Of Customer)Dim f As Predicate(Of Customer) = (c) c.State = "CA"= (c) c.State = "CA"

Dim e As Expression(Of Predicate(Of Customer))Dim e As Expression(Of Predicate(Of Customer)) = (c) c.State = "CA"= (c) c.State = "CA"

Dim e As Expression(Of Predicate(Of Customer))Dim e As Expression(Of Predicate(Of Customer)) = _= _New Expression(Of Predicate(Of Customer))(New Expression(Of Predicate(Of Customer))(

New BinaryExpression(ExpressionType.EQ,New BinaryExpression(ExpressionType.EQ,New PropertyExpression(New PropertyExpression(

New ParameterExpression(0),New ParameterExpression(0),GetType(Customer).GetProperty("State")GetType(Customer).GetProperty("State")

),),New ConstantExpression("CA")New ConstantExpression("CA")

))))

System.Query.Expression(Of T)System.Query.Expression(Of T)where T is a delegate typewhere T is a delegate type

Extension IntArrExtensions To Integer()Extension IntArrExtensions To Integer()Function Sort() As Integer()Function Sort() As Integer()

……End FunctionEnd Function

ReadOnly Property Sum() As IntegerReadOnly Property Sum() As IntegerGetGet

……End GetEnd Get

End PropertyEnd PropertyEnd ExtensionEnd Extension

Extension MethodsExtension Methods扩展模型扩展模型

Extend existing types with new methodsExtend existing types with new methods使用新方法扩展存在的类型使用新方法扩展存在的类型

Imports IntegerArrExtensionsImports IntegerArrExtensions

Dim values() As Integer = GetValues()Dim values() As Integer = GetValues()Console.WriteLine(IntegerArrExtensions.Sum(IntegerExtensions.SorConsole.WriteLine(IntegerArrExtensions.Sum(IntegerExtensions.Sort(values))t(values))

Dim values() As Integer = GetValues()Dim values() As Integer = GetValues()Console.WriteLine(values.Sort().Sum())Console.WriteLine(values.Sort().Sum())

obj.Foo(x, y)obj.Foo(x, y)

XXX.Foo(obj, x, y)XXX.Foo(obj, x, y)

Simple Type InferenceSimple Type Inference简单类型引用简单类型引用

Variable type inferred from initializerVariable type inferred from initializer由初始值推断的变量类型由初始值推断的变量类型

Dim x = 5Dim x = 5Dim s = "Hello"Dim s = "Hello"Dim d = 1.0Dim d = 1.0Dim numbers = New Integer() {1, 2, 3}Dim numbers = New Integer() {1, 2, 3}Dim orders = new Dictionary(Of Integer, Order)()Dim orders = new Dictionary(Of Integer, Order)()

All types are All types are Object!Object!

IntegerIntegerStringString

DoubleDouble

Add link to external Community websiteAdd link to external Community websiteList top 3 newsgroups related to this slideList top 3 newsgroups related to this slide

112233

Advise when your next chat isAdvise when your next chat isNext user group meeting you will be atNext user group meeting you will be atAdd Other related 3rd party sitesAdd Other related 3rd party sites

填反馈表填反馈表

讲师的讲师的Chalk TalkChalk Talk和其他和其他SessionSession

与本次主题有关的与本次主题有关的SessionSession和活动和活动