I still find it funny that if I write something that's supposed to support MySQL/PostgreSQL/SQLite it's almost always MySQL that needs tweaking or outright doesn't support something, while between PostgreSQL and SQLite it's mostly same SQL
https://changelog.com/podcast/201
> JEROD SANTO
> ...Postgres, which you say you use as kind of a reference implementation of at least the SQL stuff.
> RICHARD HIPP
> Yes.
By comparison, every single time I've touched MySQL/MariaDB I find at least one new thing that irks me to no end. UTF8 vs UTFMB4 or whatever it is for starters. Indexes on Binary data fields not being case insensitive (binary) by default, even if the default index for text is different is another. Not sure if it's still an issue, but that you can use ANSI quotes for everything but foreign key definitions was another I seem to remember. The fact that magic quotes could escape out of quoted strings another still.
And that's just off the top of my head, and doesn't get into some of the default data handling that's just bad. SQLite has some similar issues there, but imo it's far more forgivable given SQLite's footprint and embedded nature. I also really like(d) Firebird when I'd used it in the past, but it's not nearly as popular.