Upgrading Databases and Their Server Software 
You upgrade a database to a higher version and update its server software at the same time. In the following section, this procedure is known as an upgrade.
Recommendation
Make sure you have made complete backups of all data in the relevant database, and that you also have the database software of the source version. Only then you can immediately revert to the source version if an error occurs and this way avoid long periods of system downtime.
End of the recommendation.
Activities
The upgrade procedure depends on the target version as well as on the number of databases which use the software installation to be updated (See: Upgrade Strategies)