We had been using an ISAM technology called RMS (records management services) for 20+ years so had been looking for a cost-effective way to move to a relational database since 2006. I first experimented with "Oracle-RDB for OpenVMS" which seemed very promising but budget cuts prevented me from purchasing a license. After that, annual experiments with "MySQL for OpenVMS" seemed promising but all that changed in 2014 when I acquired a copy of "MariaDB-5.5-25 for OpenVMS" from Mark Berryman. Our project started off as an experiment but we soon began moving data from RMS to MariaDB. Changes are never painless and you can read the details here: OpenVMS Notes: MySQL + MariarDB
We dove in then taught ourselves as we moved along. While this was instructive, perhaps it would have been wiser to engage in a few online courses. I have lately become impressed with the quality and price of courses at udemy.com