Osquery is a an awesome host instrumentation framework from Facebook. It can instrument Mac, Linux, and Windows servers. It organises system data in tables that you can query using your favourite query language – SQL. It is SQL for your infrastructure. You can query for system intruders, system information, compliance, installed apps, running processes, and many more data points.
Osquery uses SQLite syntax for SQL. So, if you need more information about SQL syntax outside of what is covered in osquery documentation then you should give SQLite documentation a read.