I've put a whole 5 minutes of thought into this over the years, but it's something I've always thought I would like in some kind of DB tool.
Notably, being able to follow relationships easily.
Trivial use case, selecting a bunch of order rows, clicking on the "customer_id" of one of the rows, and it brings up the associated row, following the foreign key. Clicking on something else to open up the dependent tables (like the order detail lines). After a bit of clicking around, you have a subset of the DB ERD (save it has data). Then, maybe, using that as a base, you can start clicking on columns to form up a query, with all of the joins in place.
As I said, 5 minutes of thought, 30,000 ft view. But I've not seen anything like that, perhaps it's just not practical.
DBeaver has what I think you're describing (at least for me with Postgres) - when browsing tables in the 'data' view, and also for query results there is a little icon beside a data field that is a FK, and you can click it to go to the related row. Not quite the full diagram thing you're describing but I think it can do a lot more than I am aware of.
Notably, being able to follow relationships easily.
Trivial use case, selecting a bunch of order rows, clicking on the "customer_id" of one of the rows, and it brings up the associated row, following the foreign key. Clicking on something else to open up the dependent tables (like the order detail lines). After a bit of clicking around, you have a subset of the DB ERD (save it has data). Then, maybe, using that as a base, you can start clicking on columns to form up a query, with all of the joins in place.
As I said, 5 minutes of thought, 30,000 ft view. But I've not seen anything like that, perhaps it's just not practical.