Saving/Logging OPC UA Variables to a database |OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

Hello I am currently working on a project where I have several PLC machines with running OPC UA servers where I am able to read and write variables through the OPC UA protocol. I would like to be able to log variables from several machines and store them in a database with timestamps. In my vision the database would be running on a separate server and is able to access the data from the machines. In the best possible way there would be multiple databases for each machine or for example database only for running times of the machines. I am currently not very skilled about online databases like MySQL, MariaDB etc. so I am just asking for a guidance whitch database to choose from and how to finalize the idea. Ideally where to get the knowledge to be able to finalize the project. I will appreciate all the answers...