Upgrade GP10 to GP2015 and SQL 2008 to SQL2014

Hi all,

I have this environment:

GP10 and SQL2008

Need to upgrade to 

GP2015 and SQL2014 (In new server)

I understand that need to upgrade from GP10 to GP2010, then GP2010 to GP2013 and finally to GP2015. My question is, should I migrate the database to SQL2014 first? Or upgrade the GP10 to GP2010 first given that compatible issue of the GP version and SQL?

Thank you.