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.NET Framework Data Providers (ADO.NET)

A .NET Framework data provider is used for connecting to a database, executing commands, and retrieving results. Those results are either processed directly, placed in a DataSet in order to be exposed to the user as needed, combined with data from multiple sources, or remoted between tiers. .NET Framework data providers are lightweight, creating a minimal layer between the data source and code, increasing performance without sacrificing functionality.

The following table lists the data providers that are included in the .NET Framework.

.NET Framework data provider

Description

.NET Framework Data Provider for SQL Server

Provides data access for Microsoft SQL Server version 7.0 or later. Uses the System.Data.SqlClient namespace.

.NET Framework Data Provider for OLE DB

For data sources exposed by using OLE DB. Uses the System.Data.OleDb namespace.

.NET Framework Data Provider for ODBC

For data sources exposed by using ODBC. Uses the System.Data.Odbc namespace.

.NET Framework Data Provider for Oracle

For Oracle data sources. The .NET Framework Data Provider for Oracle supports Oracle client software version 8.1.7 and later, and uses the System.Data.OracleClient namespace.

EntityClient Provider

Provides data access for Entity Data Model (EDM) applications. Uses the System.Data.EntityClient namespace.

The following table outlines the four core objects that make up a .NET Framework data provider.

Object

Description

Connection

Establishes a connection to a specific data source. The base class for all Connection objects is the DbConnection class.

Command

Executes a command against a data source. Exposes Parameters and can execute in the scope of a Transaction from a Connection. The base class for all Command objects is the DbCommand class.

DataReader

Reads a forward-only, read-only stream of data from a data source. The base class for all DataReader objects is the DbDataReader class.

DataAdapter

Populates a DataSet and resolves updates with the data source. The base class for all DataAdapter objects is the DbDataAdapter class.

In addition to the core classes listed in the table earlier in this document, a .NET Framework data provider also contains the classes listed in the following table.

Object

Description

Transaction

Enlists commands in transactions at the data source. The base class for all Transaction objects is the DbTransaction class. ADO.NET also provides support for transactions using classes in the System.Transactions namespace.

CommandBuilder

A helper object that automatically generates command properties of a DataAdapter or derives parameter information from a stored procedure and populates the Parameters collection of a Command object. The base class for all CommandBuilder objects is the DbCommandBuilder class.

ConnectionStringBuilder

A helper object that provides a simple way to create and manage the contents of connection strings used by the Connection objects. The base class for all ConnectionStringBuilder objects is the DbConnectionStringBuilder class.

Parameter

Defines input, output, and return value parameters for commands and stored procedures. The base class for all Parameter objects is the DbParameter class.

Exception

Returned when an error is encountered at the data source. For an error encountered at the client, .NET Framework data providers throw a .NET Framework exception. The base class for all Exception objects is the DbException class.

Error

Exposes the information from a warning or error returned by a data source.

ClientPermission

Provided for .NET Framework data provider code access security attributes. The base class for all ClientPermission objects is the DBDataPermission class.

The .NET Framework Data Provider for SQL Server (SqlClient) uses its own protocol to communicate with SQL Server. It is lightweight and performs well because it is optimized to access a SQL Server directly without adding an OLE DB or Open Database Connectivity (ODBC) layer. The following illustration contrasts the .NET Framework Data Provider for SQL Server with the .NET Framework Data Provider for OLE DB. The .NET Framework Data Provider for OLE DB communicates to an OLE DB data source through both the OLE DB Service component, which provides connection pooling and transaction services, and the OLE DB provider for the data source.

NoteNote

The .NET Framework Data Provider for ODBC has a similar architecture to the .NET Framework Data Provider for OLE DB; for example, it calls into an ODBC Service Component.

Comparison of the dnprdnshort Data Provider for ssNoVersion and the dnprdnshort Data Provider for OLE DB

Data providers

To use the .NET Framework Data Provider for SQL Server, you must have access to SQL Server 7.0 or later versions. The .NET Framework Data Provider for SQL Server classes are located in the System.Data.SqlClient namespace. For earlier versions of SQL Server, use the .NET Framework Data Provider for OLE DB with the SQL Server OLE DB provider System.Data.OleDb.

The .NET Framework Data Provider for SQL Server supports both local and distributed transactions. For distributed transactions, the .NET Framework Data Provider for SQL Server, by default, automatically enlists in a transaction and obtains transaction details from Windows Component Services or System.Transactions. For more information, see Transactions and Concurrency (ADO.NET).

The following code example shows how to include the System.Data.SqlClient namespace in your applications.

Imports System.Data.SqlClient

The .NET Framework Data Provider for OLE DB (OleDb) uses native OLE DB through COM interop to enable data access. The .NET Framework Data Provider for OLE DB supports both local and distributed transactions. For distributed transactions, the .NET Framework Data Provider for OLE DB, by default, automatically enlists in a transaction and obtains transaction details from Windows 2000 Component Services. For more information, see Transactions and Concurrency (ADO.NET).

The following table shows the providers that have been tested with ADO.NET.

Driver

Provider

SQLOLEDB

Microsoft OLE DB provider for SQL Server

MSDAORA

Microsoft OLE DB provider for Oracle

Microsoft.Jet.OLEDB.4.0

OLE DB provider for Microsoft Jet

NoteNote

Using an Access (Jet) database as a data source for multithreaded applications, such as ASP.NET applications, is not recommended. If you must use Jet as a data source for an ASP.NET application, realize that ASP.NET applications connecting to an Access database can encounter connection problems. For help troubleshooting connection problems using ASP.NET and an Access (Jet) database, see article Q316675, "PRB: Cannot Connect to Access Database from ASP.NET" in the Microsoft Knowledge Base.

The .NET Framework Data Provider for OLE DB does not support OLE DB version 2.5 interfaces. OLE DB Providers that require support for OLE DB 2.5 interfaces will not function correctly with the .NET Framework Data Provider for OLE DB. This includes the Microsoft OLE DB provider for Exchange and the Microsoft OLE DB provider for Internet Publishing.

The .NET Framework Data Provider for OLE DB does not work with the OLE DB provider for ODBC (MSDASQL). To access an ODBC data source using ADO.NET, use the .NET Framework Data Provider for ODBC.

.NET Framework Data Provider for OLE DB classes are located in the System.Data.OleDb namespace. The following code example shows how to include the System.Data.OleDb namespace in your applications.

Imports System.Data.OleDb
NoteNote

The .NET Framework Data Provider for OLE DB requires MDAC 2.6 or a later version, and MDAC 2.8 Service Pack 1 (SP1) is recommended. You can download MDAC 2.8 SP1 from the Data Access and Storage Developer Center.

The .NET Framework Data Provider for ODBC (Odbc) uses the native ODBC Driver Manager (DM) to enable data access. The ODBC data provider supports both local and distributed transactions. For distributed transactions, the ODBC data provider, by default, automatically enlists in a transaction and obtains transaction details from Windows 2000 Component Services. For more information, see Transactions and Concurrency (ADO.NET).

The following table shows the ODBC drivers tested with ADO.NET.

Driver

SQL Server

Microsoft ODBC for Oracle

Microsoft Access Driver (*.mdb)

.NET Framework Data Provider for ODBC classes are located in the System.Data.Odbc namespace.

The following code example shows how to include the System.Data.Odbc namespace in your applications.

Imports System.Data.Odbc
NoteNote

The .NET Framework Data Provider for ODBC requires MDAC 2.6 or a later version, and MDAC 2.8 SP1 is recommended. You can download MDAC 2.8 SP1 from the Data Access and Storage Developer Center.

The .NET Framework Data Provider for Oracle (OracleClient) enables data access to Oracle data sources through Oracle client connectivity software. The data provider supports Oracle client software version 8.1.7 or a later version. The data provider supports both local and distributed transactions. For more information, see Transactions and Concurrency (ADO.NET).

The .NET Framework Data Provider for Oracle requires Oracle client software (version 8.1.7 or a later version) on the system before you can connect to an Oracle data source.

.NET Framework Data Provider for Oracle classes are located in the System.Data.OracleClient namespace and are contained in the System.Data.OracleClient.dll assembly. You must reference both the System.Data.dll and the System.Data.OracleClient.dll when you compile an application that uses the data provider.

The following code example shows how to include the System.Data.OracleClientnamespace in your applications.

Imports System.Data
Imports System.Data.OracleClient

Depending on the design and data source for your application, your choice of .NET Framework data provider can improve the performance, capability, and integrity of your application. The following table discusses the advantages and limitations of each .NET Framework data provider.

Provider

Notes

.NET Framework Data Provider for SQL Server

Recommended for middle-tier applications that use Microsoft SQL Server 7.0 or a later version.

Recommended for single-tier applications that use Microsoft Database Engine (MSDE) or SQL Server 7.0 or a later version.

Recommended over use of the OLE DB provider for SQL Server (SQLOLEDB) with the .NET Framework Data Provider for OLE DB.

For SQL Server 6.5 and earlier, you must use the OLE DB provider for SQL Server with the .NET Framework Data Provider for OLE DB.

.NET Framework Data Provider for OLE DB

Recommended for middle-tier applications that use SQL Server 6.5 or earlier.

For SQL Server 7.0 or a later version, the .NET Framework Data Provider for SQL Server is recommended.

Also recommended for single-tier applications that use Microsoft Access databases. Use of an Access database for a middle-tier application is not recommended.

.NET Framework Data Provider for ODBC

Recommended for middle and single-tier applications that use ODBC data sources.

.NET Framework Data Provider for Oracle

Recommended for middle and single-tier applications that use Oracle data sources.

The EntityClient provider is used for accessing data based on an Entity Data Model (EDM). Unlike the other .NET Framework data providers, it does not interact directly with a data source. Instead, it uses Entity SQL to communicate with the underlying data provider. For more information, see EntityClient and Entity SQL.

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