如何从 T-SQL 获取当前实例名称

How about this:

EXECUTE xp_regread @rootkey='HKEY_LOCAL_MACHINE',
@key='SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\SQl',
@value_name='MSSQLSERVER'

This will get the instance name as well. null means default instance:

SELECT SERVERPROPERTY ('InstanceName')

http://technet.microsoft.com/en-us/library/ms174396.aspx

Just found the answer, in this SO question (literally, inside the question, not any answer):

SELECT @@servername

returns servername\instance as far as this is not the default instance

SELECT @@servicename

returns instance name, even if this is the default (MSSQLSERVER)

SELECT @@servername will give you data as server/instanceName

To get only the instanceName you should run select @@ServiceName query .

I found this:

EXECUTE xp_regread
@rootkey = 'HKEY_LOCAL_MACHINE',
@key = 'SOFTWARE\Microsoft\Microsoft SQL Server',
@value_name = 'InstalledInstances'

That will give you list of all instances installed in your server.

The ServerName property of the SERVERPROPERTY function and @@SERVERNAME return similar information. The ServerName property provides the Windows server and instance name that together make up the unique server instance. @@SERVERNAME provides the currently configured local server name.

And Microsoft example for current server is:

SELECT CONVERT(sysname, SERVERPROPERTY('servername'));

This scenario is useful when there are multiple instances of SQL Server installed on a Windows server, and the client must open another connection to the same instance used by the current connection.

Why stop at just the instance name? You can inventory your SQL Server environment with following:

SELECT
SERVERPROPERTY('ServerName') AS ServerName,
SERVERPROPERTY('MachineName') AS MachineName,
CASE
WHEN  SERVERPROPERTY('InstanceName') IS NULL THEN ''
ELSE SERVERPROPERTY('InstanceName')
END AS InstanceName,
'' as Port, --need to update to strip from Servername. Note: Assumes Registered Server is named with Port
SUBSTRING ( (SELECT @@VERSION),1, CHARINDEX('-',(SELECT @@VERSION))-1 ) as ProductName,
SERVERPROPERTY('ProductVersion') AS ProductVersion,
SERVERPROPERTY('ProductLevel') AS ProductLevel,
SERVERPROPERTY('ProductMajorVersion') AS ProductMajorVersion,
SERVERPROPERTY('ProductMinorVersion') AS ProductMinorVersion,
SERVERPROPERTY('ProductBuild') AS ProductBuild,
SERVERPROPERTY('Edition') AS Edition,
CASE SERVERPROPERTY('EngineEdition')
WHEN 1 THEN 'PERSONAL'
WHEN 2 THEN 'STANDARD'
WHEN 3 THEN 'ENTERPRISE'
WHEN 4 THEN 'EXPRESS'
WHEN 5 THEN 'SQL DATABASE'
WHEN 6 THEN 'SQL DATAWAREHOUSE'
END AS EngineEdition,
CASE SERVERPROPERTY('IsHadrEnabled')
WHEN 0 THEN 'The Always On Availability Groups feature is disabled'
WHEN 1 THEN 'The Always On Availability Groups feature is enabled'
ELSE 'Not applicable'
END AS HadrEnabled,
CASE SERVERPROPERTY('HadrManagerStatus')
WHEN 0 THEN 'Not started, pending communication'
WHEN 1 THEN 'Started and running'
WHEN 2 THEN 'Not started and failed'
ELSE 'Not applicable'
END AS HadrManagerStatus,
CASE SERVERPROPERTY('IsSingleUser') WHEN 0 THEN 'No' ELSE 'Yes' END AS InSingleUserMode,
CASE SERVERPROPERTY('IsClustered')
WHEN 1 THEN 'Clustered'
WHEN 0 THEN 'Not Clustered'
ELSE 'Not applicable'
END AS IsClustered,
'' as ServerEnvironment,
'' as ServerStatus,
'' as Comments

another method to find Instance name- Right clck on Database name and select Properties, in this part you can see view connection properties in left down corner, click that then you can see the Instance name.

Just to add some clarification to the registry queries. They only list the instances of the matching bitness (32 or 64) for the current instance.

The actual registry key for 32-bit SQL instances on a 64-bit OS is:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SQL Server

You can query this on a 64-bit instance to get all 32-bit instances as well. The 32-bit instance seems restricted to the Wow6432Node so cannot read the 64-bit registry tree.

To get the list of server and instance that you're connected to:

select * from Sys.Servers

To get the list of databases that connected server has:

SELECT * from sys.databases;

You can get your server name, machine name and instance name with Transact-SQL(T-SQL) as shown below:

SELECT @@SERVERNAME                    -- DESKTOP-OVPADTC\SQLEXPRESS
SELECT SERVERPROPERTY ('ServerName')   -- DESKTOP-OVPADTC\SQLEXPRESS


SELECT HOST_NAME()                     -- DESKTOP-OVPADTC
SELECT SERVERPROPERTY ('MachineName')  -- DESKTOP-OVPADTC


SELECT @@SERVICENAME                   -- SQLEXPRESS
SELECT SERVERPROPERTY ('InstanceName') -- SQLEXPRESS