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Comment by icedchai | Hacker News Reader

Sequence diagrams are very useful for APIs and understanding protocols between systems.

ER diagrams are great for presenting a database schema (just don't get too hung up the exact arrow you're using!) When I start a new major project, one of the first things I do is an ERD. You don't need every field (column, attribute...), but the tables (entities, objects, collections, whatever you want to call it...) and their relationships are pretty important.

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I think statecharts are even more useful than sequence diagrams in documenting behaviour. Statecharts are Turing complete, and succinctly visually encode complex behaviour that is going to take reams of text to describe. Harel et al have done serious, rigourous work in developing statechart.

Yes but it seems the order is taught is important. Without actual industry experience, it never occurred to me it could be useful.

After some years working, it's clear it's useful in some capacity but it's easy to overdo it (like require every detail of the system to be in those formats) or misuse it (sequence diagram improperly documenting async flows).

As I remember ORM / NIAM diagram is more superior that it can turn into 5NF in one go (or two .. can't remember exactly)

I find it's easier to think of these data as cartesian product of a bunch of tuple. Even having table in my imagination is confusing!

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