Opens a database connection with the property settings specified by the ConnectionString.
Assembly: System.Data (in System.Data.dll)
Cannot open a connection without specifying a data source or server.
The connection is already open.
A connection-level error occurred while opening the connection. If the Number property contains the value 18487 or 18488, this indicates that the specified password has expired or must be reset. See the ChangePassword method for more information.
The SqlConnection draws an open connection from the connection pool if one is available. Otherwise, it establishes a new connection to an instance of SQL Server.
If you specify a port number other than 1433 when you are trying to connect to an instance of SQL Server and using a protocol other than TCP/IP, the method fails. To specify a port number other than 1433, include "server=machinename,port number" in the connection string, and use the TCP/IP protocol.
The following example creates a SqlConnection, opens it, and displays some of its properties. The connection is automatically closed at the end of the using block.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.