You can find out the list of locally installed SQL Server instances in the Windows registry (regedit.exe) at the following location:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\SQL |
Additionally, you can get this list by running the following command line (cmd.exe):
C:\>reg.exe query "HKLM\Software\Microsoft\Microsoft SQL Server\Instance Names\SQL"
For example, for SQL Server 2008 R2 Express default installation, the command returns:
SQLEXPRESS REG_SZ MSSQL10_50.SQLEXPRESS |
Last Update: Microsoft SQL Server 2008 R2