I've often pondered the idea of something similar to this. I'd love the idea of a note taking app as relational database.

Most of my work tends to follow a few similar formats, which I would like to create as templates that pull in data based on queries for whatever project/product/task I'm currently working on. Editing the document in current view would then modify the database, while editing the templates would allow for a quick update of all files simultaneously (i.e.- generating a test plan for a physical product of type "X" would then apply to all products of type "X").

It seems like a great way to take out the annoyance of the "little stuff" by providing a boilerplate way to get ideas off the ground.

Any ideas if this already exists, or if I'm just talking crazy?

You can achieve a lot of this with Obsidian and some plugins, like obsidian-dataview and Templater.

Might have some missing bits still, but if you're comfortable writing JavaScript (or not, honestly) it's very simple to make your own plugin to fix that, it sounds like a pretty minimal plugin after you have dataview.

https://github.com/blacksmithgu/obsidian-dataview https://github.com/SilentVoid13/Templater https://github.com/obsidianmd/obsidian-sample-plugin