Represents an open connection to a data source.
Assembly: System.Data (in System.Data.dll)
Thetype exposes the following members.
|ConnectionString||Gets or sets the string used to open a database. (Overrides DbConnection.ConnectionString.)|
|ConnectionTimeout||Gets the time to wait while trying to establish a connection before terminating the attempt and generating an error. (Overrides DbConnection.ConnectionTimeout.)|
|Container||Gets the IContainer that contains the Component. (Inherited from Component.)|
|Database||Gets the name of the current database or the database to be used after a connection is opened. (Overrides DbConnection.Database.)|
|DataSource||Gets the server name or file name of the data source. (Overrides DbConnection.DataSource.)|
|Provider||Gets the name of the OLE DB provider specified in the "Provider= " clause of the connection string.|
|ServerVersion||Gets a string that contains the version of the server to which the client is connected. (Overrides DbConnection.ServerVersion.)|
|Site||Gets or sets the ISite of the Component. (Inherited from Component.)|
|State||Gets the current state of the connection. (Overrides DbConnection.State.)|
|BeginTransaction()||Starts a database transaction with the current IsolationLevel value.|
|BeginTransaction(IsolationLevel)||Starts a database transaction with the specified isolation level.|
|ChangeDatabase||Changes the current database for an open . (Overrides DbConnection.ChangeDatabase(String).)|
|Close||Closes the connection to the data source. (Overrides DbConnection.Close().)|
|CreateCommand||Creates and returns an OleDbCommand object associated with the .|
|CreateObjRef||Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)|
|Dispose()||Releases all resources used by the Component. (Inherited from Component.)|
|EnlistDistributedTransaction||Enlists in the specified transaction as a distributed transaction.|
|EnlistTransaction||Enlists in the specified transaction as a distributed transaction. (Overrides DbConnection.EnlistTransaction(Transaction).)|
|Equals(Object)||Determines whether the specified object is equal to the current object. (Inherited from Object.)|
|GetHashCode||Serves as the default hash function. (Inherited from Object.)|
|GetLifetimeService||Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)|
|GetOleDbSchemaTable||Returns schema information from a data source as indicated by a GUID, and after it applies the specified restrictions.|
|GetSchema()||Returns schema information for the data source of this . (Overrides DbConnection.GetSchema().)|
|GetSchema(String)||Returns schema information for the data source of this using the specified string for the schema name. (Overrides DbConnection.GetSchema(String).)|
|GetSchema(String, String)||Returns schema information for the data source of this using the specified string for the schema name and the specified string array for the restriction values. (Overrides DbConnection.GetSchema(String, String).)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|InitializeLifetimeService||Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)|
|Open||Opens a database connection with the property settings specified by the ConnectionString. (Overrides DbConnection.Open().)|
|OpenAsync()||An asynchronous version of Open, which opens a database connection with the settings specified by the ConnectionString. This method invokes the virtual method OpenAsync with CancellationToken.None. (Inherited from DbConnection.)|
|OpenAsync(CancellationToken)||This is the asynchronous version of Open. Providers should override with an appropriate implementation. The cancellation token can optionally be honored.The default implementation invokes the synchronous Open call and returns a completed task. The default implementation will return a cancelled task if passed an already cancelled cancellationToken. Exceptions thrown by Open will be communicated via the returned Task Exception property.Do not invoke other methods and properties of the DbConnection object until the returned Task is complete. (Inherited from DbConnection.)|
|ReleaseObjectPool||Indicates that the object pool can be released when the last underlying connection is released.|
|ResetState||Updates the State property of the object.|
|ToString||Returns a String containing the name of the Component, if any. This method should not be overridden. (Inherited from Component.)|
|ICloneable.Clone||For a description of this member, see ICloneable.Clone.|
|IDbConnection.BeginTransaction()||Begins a database transaction. (Inherited from DbConnection.)|
|IDbConnection.BeginTransaction(IsolationLevel)||Begins a database transaction with the specified IsolationLevel value. (Inherited from DbConnection.)|
|IDbConnection.CreateCommand||Creates and returns a DbCommand object that is associated with the current connection. (Inherited from DbConnection.)|
An object represents a unique connection to a data source. With a client/server database system, it is equivalent to a network connection to the server. Depending on the functionality supported by the native OLE DB provider, some methods or properties of an object may not be available.
When you create an instance of , all properties are set to their initial values. For a list of these values, see the constructor.
You can open more than one DataReader on a single . If the OLE DB provider you use does not support more than one DataReader on a single connection, the provider implicitly opens an additional connection for each.
If the goes out of scope, it is not closed. Therefore, you must explicitly close the connection by calling Close or Dispose, or by using the object within a Using statement.
To deploy high-performance applications, you must use connection pooling. When you use the .NET Framework Data Provider for OLE DB, you do not have to enable connection pooling because the provider manages this automatically. For more information about how to use connection pooling with the .NET Framework Data Provider for OLE DB, see OLE DB, ODBC, and Oracle Connection Pooling.
If a fatal OleDbException (for example, a SQL Server severity level of 20 or greater) is generated by the method executing an OleDbCommand, the might be closed. However, the user can reopen the connection and continue.
An application that creates an instance of the object can require all direct and indirect callers to have sufficient permission to the code by setting declarative or imperative security demands. makes security demands using the OleDbPermission object. Users can verify that their code has sufficient permissions by using the OleDbPermissionAttribute object. Users and administrators can also use the Caspol.exe (Code Access Security Policy Tool) to modify security policy at the computer, user, and enterprise levels. For more information, see Code Access Security and ADO.NET.
For more information about handling warning and informational messages from the data server, see Connection Events.
The object does not support setting or retrieving dynamic properties specific to an OLE DB provider. Only properties that can be passed in the connection string for the OLE DB provider are supported.
The following example creates an OleDbCommand and an . The is opened and set as the Connection for the OleDbCommand. The example then calls ExecuteNonQuery and closes the connection. To accomplish this, ExecuteNonQuery is passed a connection string and a query string that is an SQL INSERT statement.