How to restore the old version ( SQL 2008 ) data base to higher version ( SQL 2012 )? Note: If I directly restore I get an error message.

Attach database failed for Server 'Development\\SQLSERVER'. (Microsoft.SqlServer.Smo)Database 'PS_EmpData' cannot be upgraded because its non-release version (539) is not supported by this version of SQL Server. You cannot open a database that is incompatible with this version of sqlservr.exe. You must re-create the database.

I mean, this table is quite a big database; and the time it would take to re-create with all the inserts would be unreal. We are still operating with our SQL 2008 R2 for production, but development process is underway on 2012.

Can you please provide the error message? A direct restore is possible when you upgrade you database to the same edition ie standard to standart, or enterprise to enterprise. if you are restoring a database from enterprise to standard version and using an enterprise feature then the restore can fail. Please provide error information to do a further analysis.