.NET Framework Data Providers

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. 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.
.NET Framework Data Provider for SQL Server Compact 4.0. Provides data access for Microsoft SQL Server Compact 4.0. Uses the System.Data.SqlServerCe namespace.

Core Objects of .NET Framework Data Providers

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.

.NET Framework Data Provider for SQL Server (SqlClient)

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.

Note

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.

Data providers
Comparison of the .NET Framework Data Provider for SQL Server and the .NET Framework Data Provider for OLE DB

The .NET Framework Data Provider for SQL Server classes are located in the System.Data.SqlClient namespace.

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.

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

Imports System.Data.SqlClient  
using System.Data.SqlClient;  

.NET Framework Data Provider for OLE DB

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 Component Services. For more information, see Transactions and Concurrency.

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

Note

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.

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  
using System.Data.OleDb;  

.NET Framework Data Provider for ODBC

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 Component Services. For more information, see Transactions and Concurrency.

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  
using System.Data.Odbc;  

Note

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.

.NET Framework Data Provider for Oracle

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.

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.OracleClient namespace in your applications.

Imports System.Data  
Imports System.Data.OracleClient  
using System.Data;  
using System.Data.OracleClient;  

Choosing a .NET Framework Data Provider

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.

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

Recommended over use of the OLE DB provider for SQL Server (SQLOLEDB) with the .NET Framework Data Provider for OLE DB.
.NET Framework Data Provider for OLE DB For SQL Server, the .NET Framework Data Provider for SQL Server is recommended instead of this provider.

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.

EntityClient Provider

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.

See Also

ADO.NET Overview
Retrieving and Modifying Data in ADO.NET
ADO.NET Managed Providers and DataSet Developer Center