SQL Server: How to SELECT the installation path

c:Program FilesMicrosoft SQL ServerMSSQL.7MSSQL

m:CustomInstanceMSSQL

select filename from sysaltfiles
where name = db_name()

Server: Msg 208, Level 16, State 1, Line 1
Invalid object name 'sysaltfiles'.

select filename from master.dbo.sysaltfiles
where name = db_name()

filename
----------------

(0 row(s) affected)

declare @rc int, @dir nvarchar(4000)

exec @rc = master.dbo.xp_instance_regread
      N'HKEY_LOCAL_MACHINE',
      N'SoftwareMicrosoftMSSQLServerSetup',
      N'SQLPath',
      @dir output, 'no_output'
select @dir AS InstallationDirectory

declare @rc int, @dir nvarchar(4000)

exec @rc = master.dbo.xp_instance_regread
      N'HKEY_LOCAL_MACHINE',
      N'SoftwareMicrosoftMSSQLServerMSSQLServer',
      N'BackupDirectory',
      @dir output, 'no_output'
select @dir AS BackupDirectory

Declare @Path as varchar(100);
Set @Path = NULL

Exec master..xp_regread 'HKEY_LOCAL_MACHINE', 'SOFTWAREMicrosoftMicrosoft SQL Server70ToolsClientSetup', 'SQLPath', @Path OUTPUT
Select @Path as [Sql Server 7.0 path]

Set @Path = NULL
Exec master..xp_regread 'HKEY_LOCAL_MACHINE', 'SOFTWAREMicrosoftMicrosoft SQL Server80ToolsClientSetup', 'SQLPath', @Path OUTPUT
Select @Path as [Sql Server 2000 path]

Set @Path = NULL
Exec master..xp_regread 'HKEY_LOCAL_MACHINE', 'SOFTWAREMicrosoftMicrosoft SQL Server90ToolsClientSetup', 'SQLPath', @Path OUTPUT
Select @Path as [Sql Server 2005 path]

Set @Path = NULL
Exec master..xp_regread 'HKEY_LOCAL_MACHINE', 'SOFTWAREMicrosoftMicrosoft SQL Server100ToolsClientSetup', 'SQLPath', @Path OUTPUT
Select @Path as [Sql Server KATMAI path]

select filename from sysaltfiles
where name = db_name()