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System.Data Namespaces

The System.Data namespaces contain classes for accessing and managing data from diverse sources. The top-level namespace and a number of the child namespaces together form the ADO.NET architecture and ADO.NET data providers. For example, providers are available for SQL Server, Oracle, ODBC, and OleDB. Other child namespaces contain classes used by the ADO.NET Entity Data Model (EDM) and by WCF Data Services.

System.DataThe System.Data namespace provides access to classes that represent the ADO.NET architecture. ADO.NET lets you build components that efficiently manage data from multiple data sources.
System.Data.CommonThe System.Data.Common namespace contains classes shared by the .NET Framework data providers.
System.Data.Common.CommandTreesThe System.Data.Common.CommandTrees namespace provides classes to build expressions that make up a command tree.
System.Data.DesignThe System.Data.Design namespace contains classes that can be used to generate a custom typed-dataset.
System.Data.Entity.DesignThe System.Data.Entity.Design namespace contains classes to generate Entity Data Model (EDM) files and object source code.
System.Data.Entity.Design.AspNetThe System.Data.Entity.Design.AspNet namespace contains the Entity Data Model (EDM) build providers for the ASP.NET build environment.
System.Data.Entity.Design.PluralizationServicesThe PluralizationServices namespace provides classes for changing words from singular to plural form, and vice versa.
System.Data.EntityClientThe System.Data.EntityClient namespace is the .NET Framework Data Provider for the Entity Framework.
System.Data.LinqThe System.Data.Linq namespace contains classes that support interaction with relational databases in LINQ to SQL applications.
System.Data.Linq.MappingThe System.Data.Linq.Mapping namespace contains classes that are used to generate a LINQ to SQL object model that represents the structure and content of a relational database.
System.Data.Linq.SqlClientThe System.Data.Linq.SqlClient namespace contains provider classes for communicating with SQL Server and classes that contain query helper methods.
System.Data.Linq.SqlClient.ImplementationThe System.Data.Linq.SqlClient.Implementation namespace contains types that are used for the internal implementation details of a SQL Server provider.
System.Data.MappingThe System.Data.Mapping namespace provides access to the MappingItemCollection and StorageMappingItemCollection classes.
System.Data.Metadata.EdmThe System.Data.Metadata.Edm namespace contains a set of types that represent concepts throughout the models used by the Entity Framework and a set of classes that help applications to work with metadata. 
System.Data.ObjectsThe System.Data.Objects namespace includes classes that provide access to the core functionality of Object Services. These classes enable you to query, insert, update, and delete data by working with strongly typed CLR objects that are instances of entity types. Object Services supports both Language-Integrated Query (LINQ) and Entity SQL queries against types that are defined in an Entity Data Model (EDM). Object Services materializes the returned data as objects and propagates object changes back to the data source. It also provides facilities for tracking changes, binding objects to controls, and handling concurrency. For more information, see Object Services Overview (Entity Framework).
System.Data.Objects.DataClassesThe System.Data.Objects.DataClasses namespace includes classes that are base classes for types that are defined in an Entity Data Model (EDM), base classes for the types that are returned by navigation properties, and classes that define attributes that map common language runtime (CLR) objects to types in the conceptual model.
System.Data.Objects.SqlClientThe System.Data.Objects.SqlClient namespace provides the SqlFunctions class, which contains common language runtime (CLR) methods that translate to database functions. Methods in the SqlFunctions class can only be used in LINQ to Entities queries.
System.Data.OdbcThe System.Data.Odbc namespace is the .NET Framework Data Provider for ODBC.
System.Data.OleDbThe System.Data.OleDb namespace is the.NET Framework Data Provider for OLE DB.
System.Data.OracleClientThe System.Data.OracleClient namespace is the .NET Framework Data Provider for Oracle.
System.Data.ServicesProvides access to classes used to build WCF Data Services.
System.Data.Services.BuildProviderClasses in this namespace generate C# or Visual Basic code for a WCF Data Services client application based on the metadata returned by the data service.
System.Data.Services.ClientRepresents the .NET Framework client library that applications can use to interact with WCF Data Services.
System.Data.Services.CommonImplements functionality common to both WCF Data Services client and server runtimes.
System.Data.Services.DesignUsed by the code generation command line tools and tools in Visual Studio to generate strongly-typed client side objects for communicating with data services.
System.Data.Services.InternalThis class is not for public use and is used internally by the system to implement support for queries with eager loading of related entities.
System.Data.Services.ProvidersProvides a series of interfaces that are implemented to define a custom data service provider for WCF Data Services. 
System.Data.SqlThe System.Data.Sql namespace contains classes that support SQL Server-specific functionality.
System.Data.SqlClientThe System.Data.SqlClient namespace is the.NET Framework Data Provider for SQL Server.
System.Data.SqlTypesThe System.Data.SqlTypes namespace provides classes for native data types in SQL Server. These classes provide a safer, faster alternative to the data types provided by the .NET Framework common language runtime (CLR). Using the classes in this namespace helps prevent type conversion errors caused by loss of precision. Because other data types are converted to and from SqlTypes behind the scenes, explicitly creating and using objects within this namespace also yields faster code.