Ask HN: Tools for turning DB records into graphs

I (like most developers) have plenty of relations stored in RDBMS (MySQL, PostgreSQL, etc) across many projects.

Are there any open source projects we can use to graph relations (often foreign keys) to see clusters, flows, networks, and relationships from these databases we already have?

- Most connected users

- Most referenced issue cluster

- Most common time-of-day for X

- Number of relationships

I (like most people) would prefer not to have to create a schema and import all the data. It would be nice if the tool could read directly (or semi-directly) from an SQL database.