> That's absolutely true and it's something every other RDBMS does.
To various degrees, and there's violating the standard (by adding non-standard construct) and violating the standard (by failing to implement a feature entirely, or implementing it with different syntax or semantics).
http://troels.arvin.dk/db/rdbms/ is generally my go-to page for that stuff as it lists standard solutions (with reference and mention of the features used being optional if applicable) and alternative db-specific solutions (exclusive or inclusive of the database accepting the standard solution). Sadly it is not really up to date, and obviously does not go through the whole standard.
To various degrees, and there's violating the standard (by adding non-standard construct) and violating the standard (by failing to implement a feature entirely, or implementing it with different syntax or semantics).
http://troels.arvin.dk/db/rdbms/ is generally my go-to page for that stuff as it lists standard solutions (with reference and mention of the features used being optional if applicable) and alternative db-specific solutions (exclusive or inclusive of the database accepting the standard solution). Sadly it is not really up to date, and obviously does not go through the whole standard.