Creating a Valid Connection String Using Shared Memory Protocol
Connections to Microsoft SQL Server from a client running on the same computer use the shared memory protocol. Shared memory has no configurable properties. Shared memory is always tried first, and cannot be moved from the top position of the Enabled Protocols list in the Client Protocols Properties list. The Shared Memory protocol can be disabled, which is useful when troubleshooting one of the other protocols.
You cannot create an alias using the shared memory protocol, but if shared memory is enabled, then connecting to the Database Engine by name, creates a shared memory connection. A shared memory connection string uses the format lpc:<servername>[\instancename].
Connecting to the Local Server
When connecting to SQL Server running on the same computer as the client, you can use (local) as the server name. This is not encouraged as it leads to ambiguity, however it can be useful when the client is known to be running on the intended computer. For instance, when creating an application for mobile disconnected users, such as a sales force, where SQL Server will run on laptop computers and store project data, a client connecting to (local) would always connect to the SQL Server running on the laptop. The word localhost or a period (.) can be used in place of (local).
Verifying your Connection Protocol
The following query will return the protocol used for the current connection.
SELECT net_transport
FROM sys.dm_exec_connections
WHERE session_id = @@SPID;
Examples:
The following names will connect to the local computer with the shared memory protocol if it is enabled:
<servername>
<servername>\<instancename>
(local)
localhost
You cannot create an alias for a shared memory connection.
Note
Specifying an IP Address in the Server box will result in a TCP/IP connection.
See Also
Reference
Creating a Valid Connection String Using TCP/IP
Creating a Valid Connection String Using Named Pipes
Creating a Valid Connection String Using VIA Protocol