We are updating our current OJS version 3.2.1.2 to 3.3.0.15. There is a huge difference between old and new ojs database tables. Manually changing table properties/columns requires a lot time and R&D.
Is there any way to update ojs without losing data?
Database schema upgrades are done by the upgrade script. Did you read the Upgrade Guide https://docs.pkp.sfu.ca/dev/upgrade-guide/en/ ?