Function Get-InstalledSQLVersions() {
	[CmdletBinding()]
	param ()
	
	$versions = @()
	$instances = (get-itemproperty 'HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server').InstalledInstances
	foreach ($instance in $instances)
	{
	   $instanceName = (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\SQL').$instance
	   $versions += (Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server\$instanceName\Setup").Version
	}
	
	return $versions | Sort-Object | Get-Unique
}