Represents an open connection to a SQL Server database. This class cannot be inherited.
Assembly: System.Data (in System.Data.dll)
Initializes a new instance of theclass.
Initializes a new instance of theclass when given a string that contains the connection string.
Initializes a new instance of the SqlCredential object that contains the user ID and password.class given a connection string, that does not use Integrated Security = true and a
Gets or sets the access token for the connection.
The connection ID of the most recent connection attempt, regardless of whether the attempt succeeded or failed.
Gets or sets the time-to-live for column encryption key entries in the column encryption key cache for the Always Encrypted feature. The default value is 2 hours. 0 means no caching at all.
Gets or sets a value that indicates whether query metadata caching is enabled (true) or not (false) for parameterized queries running against Always Encrypted enabled databases. The default value is true.
Allows you to set a list of trusted key paths for a database server. If while processing an application query the driver receives a key path that is not on the list, the query will fail. This property provides additional protection against security attacks that involve a compromised SQL Server providing fake key paths, which may lead to leaking key store credentials.
Gets or sets the string used to open a SQL Server database.(Overrides DbConnection.ConnectionString.)
Gets the time to wait while trying to establish a connection before terminating the attempt and generating an error.(Overrides DbConnection.ConnectionTimeout.)
Gets or sets the SqlCredential object for this connection.
Gets the name of the current database or the database to be used after a connection is opened.(Overrides DbConnection.Database.)
Gets the name of the instance of SQL Server to which to connect.(Overrides DbConnection.DataSource.)
Gets or sets the FireInfoMessageEventOnUserErrors property.
Gets the size (in bytes) of network packets used to communicate with an instance of SQL Server.
Gets a string that contains the version of the instance of SQL Server to which the client is connected.(Overrides DbConnection.ServerVersion.)
Indicates the state of the DbConnection.State.)during the most recent network operation performed on the connection.(Overrides
When set to true, enables statistics gathering for the current connection.
Gets a string that identifies the database client.
Starts a database transaction.
Starts a database transaction with the specified isolation level.
Starts a database transaction with the specified isolation level and transaction name.
Starts a database transaction with the specified transaction name.
Changes the current database for an open DbConnection.ChangeDatabase(String).).(Overrides
|ChangePassword(String, SqlCredential, SecureString)|
Changes the SQL Server password for the user indicated in the SqlCredential object.
Changes the SQL Server password for the user indicated in the connection string to the supplied new password.
Empties the connection pool.
Empties the connection pool associated with the specified connection.
Closes the connection to the database. This is the preferred method of closing any open connection.(Overrides DbConnection.Close().)
Creates and returns a SqlCommand object associated with the .
Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.(Inherited from MarshalByRefObject.)
Enlists in the specified transaction as a distributed transaction.
Enlists in the specified transaction as a distributed transaction.(Overrides DbConnection.EnlistTransaction(Transaction).)
Determines whether the specified object is equal to the current object.(Inherited from Object.)
Serves as the default hash function. (Inherited from Object.)
Retrieves the current lifetime service object that controls the lifetime policy for this instance.(Inherited from MarshalByRefObject.)
Returns schema information for the data source of this DbConnection.GetSchema(String).)using the specified string for the schema name.(Overrides
Returns schema information for the data source of this DbConnection.GetSchema(String, String).)using the specified string for the schema name and the specified string array for the restriction values.(Overrides
Obtains a lifetime service object to control the lifetime policy for this instance.(Inherited from MarshalByRefObject.)
An asynchronous version of Open, which opens a database connection with the property settings specified by the ConnectionString. The cancellation token can be used to request that the operation be abandoned before the connection timeout elapses. Exceptions will be propagated via the returned Task. If the connection timeout time elapses without successfully connecting, the returned Task will be marked as faulted with an Exception. The implementation returns a Task without blocking the calling thread for both pooled and non-pooled connections.(Overrides DbConnection.OpenAsync(CancellationToken).)
Registers the column encryption key store providers.
If statistics gathering is enabled, all values are reset to zero.
Returns a name value pair collection of statistics at the point in time the method is called.
Begins a database transaction.(Inherited from DbConnection.)
Creates a new object that is a copy of the current instance.
A SqlDataAdapter and SqlCommand to increase performance when connecting to a Microsoft SQL Server database. For all third-party SQL Server products, and other OLE DB-supported data sources, use OleDbConnection.object represents a unique session to a SQL Server data source. With a client/server database system, it is equivalent to a network connection to the server. is used together with
When you create an instance of, all properties are set to their initial values. For a list of these values, see the constructor.
See ConnectionString for a list of the keywords in a connection string.
If thegoes out of scope, it won't be closed. Therefore, you must explicitly close the connection by calling Close or Dispose. Close and Dispose are functionally equivalent. If the connection pooling value Pooling is set to true or yes, the underlying connection is returned back to the connection pool. On the other hand, if Pooling is set to false or no, the underlying connection to the server is actually closed.
Login and logout events will not be raised on the server when a connection is fetched from or returned to the connection pool, because the connection is not actually closed when it is returned to the connection pool. For more information, see SQL Server Connection Pooling (ADO.NET).
To ensure that connections are always closed, open the connection inside of a using block, as shown in the following code fragment. Doing so ensures that the connection is automatically closed when the code exits the block.
To deploy high-performance applications, you must use connection pooling. When you use the .NET Framework Data Provider for SQL Server, you do not have to enable connection pooling because the provider manages this automatically, although you can modify some settings. For more information, see SQL Server Connection Pooling (ADO.NET).
If a SqlException is generated by the method executing a SqlCommand, the remains open when the severity level is 19 or less. When the severity level is 20 or greater, the server ordinarily closes the . However, the user can reopen the connection and continue.
An application that creates an instance of the SqlClientPermission object. Users can verify that their code has sufficient permissions by using the SqlClientPermissionAttribute object. Users and administrators can also use the Caspol.exe (Code Access Security Policy Tool) to modify security policy at the machine, user, and enterprise levels. For more information, see Security in the .NET Framework. For an example demonstrating how to use security demands, see Code Access Security and ADO.NET.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
For more information about handling warning and informational messages from the server, see Connection Events. SQL Server engine errors and error messages are documented in SQL Server Books Online.
You can force TCP instead of shared memory. You can do that by prefixing tcp: to the server name in the connection string or you can use localhost.
The following example creates a SqlCommand and a . The is opened and set as the Connection for the SqlCommand. The example then calls ExecuteNonQuery. To accomplish this, the ExecuteNonQuery is passed a connection string and a query string that is a Transact-SQL INSERT statement. The connection is closed automatically when the code exits the using block.
Available since 1.1
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.