Between SQL Server 2005 and 2012, Microsoft experimented with (also called RANU — Run As Normal User). An application could attach a database file ( .mdf ) directly via a connection string without a full service installation.
if ($Action -eq "Install") Out-Null Set-ItemProperty -Path $RegPath -Name "SQLArg0" -Value "-s$InstanceName" Write-Host "Service installed. Starting..." net start "MSSQL $$InstanceName" ms sql server express portable
elseif ($Action -eq "Remove") net stop "MSSQL $$InstanceName" 2>$null sc.exe delete "MSSQL $$InstanceName" Remove-Item -Path $RegPath -Recurse -Force -ErrorAction SilentlyContinue Write-Host "Service removed from this machine." Between SQL Server 2005 and 2012, Microsoft experimented
Given these constraints, any "portable" solution is, by definition, a hack. However, a surprisingly robust set of hacks exists. If you search GitHub or StackOverflow for "SQL Server Express portable," you will find three distinct archetypes. Each offers a different trade-off between convenience, authenticity, and system impact. Approach 1: The User-Instance Legacy (SQL Server Express 2008–2012) Historical context, but still relevant for legacy systems. Starting