Oracle database 12c upgrade to 19c I was asked to advise some business analyst on migration from Oracle DB 12c to 19c. The thing is I have never used or done anything related to Oracle DB. From my experience with MSSQL during upgrade I know that some features became deprecated hence it required a bit of manual work for example re write custom made stored procedures, there were some issues with indexes and etc..

The good thing with MSSQL was it told you before upgrade what issues you will encounter and what is deprecated. Can you do check it similarly in Oracle Db aswell?

Also, please share your upgrade stories, did it went smooth? Did you encountered any issues afterwards? What should be kept in mind (that might break after upgrade) before upgrading? Also I would appreciate any related articles/videos/etc...
Upgrading 12c to 18c or 19c should not be a problem. I don't think that 19c is that different from 12c. The dbua tool should be able to do the upgrade. You still need to test with a test database. But running the dbua tool should work. Going from pre-12c to 19c is a much bigger issue depending on what features are used.