ASP网页设计ADO.NET 2.0 Feature Matrix

Access是一种桌面数据库，只适合数据量少的应用，在处理少量数据和单机访问的数据库时是很好的，效率也很高。但是它的同时访问客户端不能多于4个。access数据库有一定的极限，如果数据达到100M左右，很容易造成服务器iis假死，或者消耗掉服务器的内存导致服务器崩溃。adoADO.NET2.0FeatureMatrix
BobBeauchemin
DevelopMentor
July2004
Appliesto:
MicrosoftADO.NET2.0
MicrosoftSQLServer2005
Summary:ADO.NET2.0includesanewbase-classprovidermodel,featuresforallproviders,and
changestoSystem.Data.SqlClient.Getanoverviewofthesenewfeatures,examplesoftheiruse,anda
chartofwhichfeaturesareprovider-neutralandSqlClient-specific.(14printedpages)
Contents
TheBase-Class-BasedProviderModel
ConnectionPoolingEnhancements
AsynchronousCommands
BulkImport
ProviderStatistics
AttachDbFileName
SQLServer2005-SpecificFeaturesinSqlClient
Conclusion
ADO.NET2.0comeswithaplethoraofnewfeatures.Thisincludesanewbase-classCbasedprovider
modelandfeaturesthatallproviderscantakeadvantageof,aswellaschangesthatarespecificto
System.Data.SqlClient.Becausethe.NETFramework2.0isbeingreleasedinconjunctionwithSQL
Server2005,someofthesefeaturesrequireSQLServer2005tobeusable.Thisarticleismeanttoserve
asanoverviewandroadmapofthenewfeatures,giveexamplesoftheiruse,andincludesachartof
whichfeaturesareprovider-neutralandwhichareSqlClient-specific.Infuturearticlesinthisseries,Ill
begoingoversomeofthefeaturesingreaterdetail.Inaddition,therearemanynewfeaturesofthe
DataSetandfriends;thesewillbecoveredinfuturearticles.
TheBase-Class-BasedProviderModel
InADO.NET1.0and1.1,providerwritersimplementedaseriesofprovider-specificclasses.Generic
codingwaspossiblebasedonthefactthateachoftheclassesimplementedagenericinterface.Asan
example,System.Data.SqlClientcontainstheclassSqlConnectionandthisclassimplements
IDbConnection.System.Data.OracleClientcontainstheclassOracleConnection,whichalso
implementsIDbConnection.Theprovider-specificclassescouldimplementdata-sourceCspecific
propertiesandmethods,e.g.,SqlConnectionimplementstheDatabasepropertyandthe
ChangeDatabasemethod.OracleConnectiondoesnot,becausetheOracledatabasedoesnothavethe
conceptofmultiple"databases"(theseareknownascatalogsinANSISQL)perdatabaseinstance.The
newprovidermodelinADO.NET2.0isbasedonaseriesofbaseclassesinSystem.Data.Common.
Theseprovideabasicimplementationofcommonfunctionalityand,ofcourse,eachofthebaseclasses
implementsthestill-requiredgenericinterfaceforbackwardcompatibility.Providerwriterscanchooseto
usethebaseclassesorsupporttheinterfaces.
Thereweretwoexceptionstotheinterfacemodelinpreviousversions,the
DataAdapter/DbDataAdapterandCommandBuilder.TheCommandBuilderclassprovidesan
automaticimplementationofINSERT,UPDATE,andDELETEcommandsthatusethesamecolumn-set,
forasimpleSELECTcommand.ExtendingaCommandBuilderwhilekeepingthebasealgorithmthatit
usedtocreateactionstatementswasnotpossiblebecausetheSqlCommandBuilderwasasealedclass.
AlthoughthereisstillnowaytoreusetheSqlCommandBuilderparameterparser,thereisa
DbCommandBuilderbaseclassinSystem.Data.Common.Therearenewfeaturesexposedatthe
base-classlevelintheseclasses,too.TheDataAdapter/DbDataAdapterbaseclassesexposemechanisms
forpushingprovider-specifictypeslikeSQLServerSqlTypesintotheDataSet(the
ReturnProviderSpecificTypesproperty)andforbatchupdates(StatementType.Batchenumeration
valueandUpdateBatchSizeproperty).TheDbCommandBuildercommonbaseclassincludesaproperty
toindicateconcurrencypolicychoices(theConflictDetectionproperty).
ProviderFactories
Oneofthecomplicationsoftheinterface-basedapproachinADO.NET1.0and1.1isthatyoucantcalla
constructoronaninterface.Youmustcreateaconcreteinstanceofaspecificclass.PreviousAPIslike
OLEDBandADOworkedaroundthisbyoverloadingtheconnectionstring.Theconnectionstring
containedtheCOMPROGIDoftheprovider,andthecorrectDataSourceclasswascreatedbasedonthis
PROGID.ThiswaspossiblebecauseOLEDBDataSourcePROGIDswerestoredintheregistry.
VB6ADOcode,Connectionisaninterface(actuallyits_Connection)
DimconnasConnection
notethatthedefaultproviderisMSDASQL,theOLEDBproviderforODBC
thisusestheOLEDBproviderforSQLServer
conn.ConnectionString="provider=sqloledb;.."otherparameters
deleted
conn.Open
ADO.NET2.0hasasolutionforthis.EachdataproviderregistersaProviderFactory</p>源代码保护方面其实现在考虑得没那么多了..NET也可以反编译.ASP写得复杂的话别人能看得懂的话.他也有能力自己写了.这方面担心的倒不太多.纵观现在网上可以下载的那些所谓BBS还有什么网站等等的源代码

仓酷云

不能只是将它停留在纸上谈兵的程度上。

Application:这个存储服务端的数据，如果不清除，会直到web应用程序结束才清除(例如重启站点)

ASP.Net和ASP的最大区别在于编程思维的转换，而不仅仅在于功能的增强。ASP使用VBS/JS这样的脚本语言混合html来编程，而那些脚本语言属于弱类型、面向结构的编程语言，而非面向对象，这就明显产生以下几个问题：

尽管MS自己讲C#内核中更多的象VC，但实际上我还是认为它和Java更象一些吧。首先它是面向对象的编程语言，而不是一种脚本，所以它具有面向对象编程语言的一切特性，比如封装性、继承性、多态性等等，这就解决了刚才谈到的ASP的那些弱点。

ASP.Net摆脱了以前ASP使用脚本语言来编程的缺点，理论上可以使用任何编程语言包括C++,VB,JS等等，当然，最合适的编程语言还是MS为.NetFrmaework专门推出的C(读csharp)，它可以看作是VC和Java的混合体吧。

Session:这个存储跟客户端会话过程的数据，默认20分钟失效

学习是为了用的，是为了让你的程序产生价值，把握住这个原则会比较轻松点。除此之外，课外时间一定要多参加一些社会实践活动，来锻炼自己的能力。