This is one of the questies I try to answer at https://modern-sql.com/

Your website is great and I regularly check it to see what's new in various implementations. Unfortunately it seems that many databases don't support many modern SQL features yet. Any ideas as to why?

> Unfortunately it seems that many databases don't support many modern SQL features yet. Any ideas as to why?

I'd guess the incentive structure is the opposite of what you're implying; the same reason why every cordless drill manufacturer has their own battery connector: vendor lock in fuels private planes and shareholder reports, versus being compatible means no one is forced to buy your batteries and thus profits are `$total - $forced_purchases`

This situation gets even worse in the case of a standard without any objective way of knowing one is in compliance. Having a badge on the mysql.com website saying "now featuring SQL:2023 compliance!11" sells how many more support contracts exactly?

That's a good point. Additionally, it seems the standard isn't freely available and I doubt most of the developers of existing SQL DBs partecipate in drafting new standards. It seems it is doomed to diverge even further, which begs the question whether is it relevant anymore to have the SQL standard at all

I can say that none of Oracle, Sybase, or Microsoft Sql Server really aim at conforming to the standard. While they will often try to use standard syntax for new features if such syntax exists, there is tons of old non-conforming syntax that there seems to be no real effort in addressing, even by adding new options, etc. Some of these mean really common features deviate significantly from what the standard requires.

PostgreSQL does mostly aim at conforming to the standard. They will invent new syntax when needed, But compared to the those previously mentioned, Postgres seems to prefer to stick closer to the standard whenever possible, including adding standard syntax for existing features whenever possible.

PostgreSQL does have some places where there is deliberate non-conformance (beyond just incompletely implemented features). They document many deliberate deviations (other than unimplemented or partially implemented features) and if they think they can be fixed in the future or not: https://wiki.postgresql.org/wiki/PostgreSQL_vs_SQL_Standard . Looking at the list I'd say only one especially likely to bite a developer is the default escape character for LIKE clauses, or the non-standard trailing space behavior for character(n) datatypes (but who used fixed length character datatypes instead of varchar or text?). And obviously not yet implemented features could bite people, but many such features are optional to implement anyway, so...

I cannot speak about MySQL or MariaDB, due to insufficient familiarity.