In order to upgrade the SQL Database from 2012 to 2014 SP2, ensure the Symantec Mangement Platform (SMP) Server is running with 8.0 HF4 (8.0.3396) version and above, in case it is not upgraded (as given in page# 12 in the ITMS Support Matrix - HOWTO9965).
Follow below steps:
Take a complete backup of 'Symantec_CMDB' SQL Database instance.
If the SMP server is running on a VM, then a snapshot can be taken.
Stop all the Altiris Services and also the World Wide Web Publishing Service from services.msc. The Altiris Service should be stopped while upgrading SQL to prevent any errors from being produced in the logs and also to prevent anything new from being written to the Database during the upgrade.