I point out the project https://github.com/amusarra/liferay-portal-database-all-in-one-support which groups the support for the three commercial databases for versions 7.0, 7.1 and 7.2 of Liferay.
This project add support to the Oracle Database, SQL Server and IBM DB2 database. Liferay has performed refactorting the code so that it is possible and easy to add support for databases no longer supported OOTB (out-of-the-box). The last version (1.1.4) of the driver works with the Liferay 7.2.1 CE GA2.
You can download the latest version binary jar from Maven Central Repository liferay-portal-database-all-in-one-support (https://search.maven.org/#search%7Cga%7C1%7Cit.dontesta), by doing so you can avoid doing the build.
I invite you to read the article How to build a Docker Liferay 7.2 image with the Oracle Database support (https://www.dontesta.it/en/2019/08/21/how-to-build-a-docker-liferay-7-2-image-with-the-oracle-database-support/) which may be interesting for you.