It's really not very difficult, I'm a programmer by profession but I'm only just picking up c#.
1) Install MySQL assemblies (Obviously you'd need to do do the ones that match your target DB) (https://dev.mysql.com/downloads/connector/net/6.9.html)
2) Convert the example I referred to earlier. (Samples/c#/DatabaseDataStore)
The queries aren't anything complicated. One thing I did notice is that it is noticeably slower retrieving the data when backtesting than the native RE binary store. It does all of the lookups by symbol so if you are have 500 symbols it does 500 queries for everything. It could be allot quicker if it combined those queries into one.
I've attached my file plugin here in it's current state, might give you somewhere to start. I don't have any experience with MariaDB or TukuDB but I do use Percona. If your target databases work the same as Percona you should be able to use the standard MySQL client as it is a drop in replacement.