I explain better my question.

I need to install SQL Server 2012 on a new database server.

SQL Server 2012 isn't more sold and so I'm constrained to buy SQL Server 2014 for my customer.

I know that I can downgrade from SQL Server 2014 to SQL Server 2012.

I can think that this downgrade it isn't simply to set the compatibility level of the databases to put on

the SQL Server 2014 instance but I can think that the database platform must function as a SQL Server 2012

installation.