Some of it is in the standard, some of it is PG specific. MySQL is pretty terrible and doesn't support any of it that I'm aware of. I expect Oracle has their own versions of much of this stuff, but I've made it a hobby in my life to not learn Oracle.
Oracle has subquery factoring (the "with" clause) and recursion; native arrays, hash maps, collections, nested tables, and other complex data types; remote database links; queues (similar to listen/notify); regex querying; attribute-level timezone support; extremely powerful window functions; text search; tons of built-in crypto (if you really insist); and most of the related things on this list.
The biggest killers (vs. postgres): no simple helpers (generate_series, for example, is achievable with simple, efficient recursion, but you have to write the whole statement); a truly antiquated client program (sqlplus); built-in json, but you do have associative arrays/hash maps and nested tables, so you can achieve exactly the same thing, and it's indexable*; and range types (meh imo).
I think I've had Oracle blow up on multiple AS statements, so that's one place where Postgres would come out well in front.
Basically WITH-AS lets you declared temporary named subqueries. That is, a pretty stock standard programming technique -- give a name to a fiddly expression to simplify subsequent code. Very useful.
Oracle has lots of annoyances though. No SERIAL or IDENTITY type. Having to write the same boilerplate sequence/insert trigger/update trigger over and over and over is very tedious and a recipe for subtle errors when you forget one of them or mess it up.
No boolean type in SQL. I don't even know what to say about that.
"No boolean type in SQL. I don't even know what to say about that."
Tom ties himself into unbelievable knots trying to defend this. It's the purest form of technical Stockholm Syndrome I've ever seen from a putatively intelligent person.
It's worth noting that using some of these features bump you up into a different pricing tier. And last time I checked the usual way to achieve a recursive query was with the non-standard "CONNECT BY" syntax. I have found rlwrap does a lot to mitigate the pain of sqlplus, but I still use it (and Oracle) as little as I can possibly get away with.
I actually wind up using both. But SQL Developer is pretty heavy and I prefer using psql to a GUI tool with Postgres, so I wind up in sqlplus a lot (when dealing with Oracle, which is seldom).
