The 2012 release introduced several major advancements still relevant for maintaining legacy apps:
This is the most reliable and official way to obtain a clean ISO. Subscribers can log into the Visual Studio Subscriptions portal to find legacy software including the 2012 Developer Edition. Sql Server 2012 Developer Edition Download Iso
Massive performance boosts for data warehousing queries. The 2012 release introduced several major advancements still
SQL Server 2012 Developer Edition remains a foundational tool for legacy database management, offering the full power of the Enterprise Edition specifically for non-production development and testing. Sql Server 2012 Developer Edition Download Iso