Hi

I have created some SQL database query plugin opcodes for Csound which are available here as an initial beta version:
https://github.com/1bpm/csound-sqldb

Currently they support SQLite, MySQL and PostgreSQL. I have only been able to test on Linux so any further feedback would be appreciated. They will need a recent build of Csound from the develop branch on Github.
I have not encountered any operational problems when testing but conversely I am not completely sure on the best practices for using third party libraries in plugin opcodes, so again I would be grateful for any feedback in that regard.

There are several examples included and usage is outlined in OpcodeDocumentation.md
There are three approaches: i rate which works as expected, k rate which runs queries asynchronously given a trigger and returns a trigger when complete, and k rate blocking which are for non-realtime or special purposes (see doc/examples).

all the best
Richard