Why does no database fully support ANSI or ISO SQL standards?

Question

If I were designing a oil refinery, I wouldn\'t expect that materials from different vendors would not comply with published standards in subtle yet important ways. Pipework, v

Answer 1

The real reason: most "developers" are client-centric coders, and therefore neither understand nor care about Dr. Codd's 12 rules. This is also why MySql, which isn't a relational database in any significant manner, is frequently seen in webKiddie development. Such developers only want rudimentary SELECT, UPDATE, DELETE parsing. They eschew constraints of any kind, preferring to "do it in the application". Reactionary 1960's applications are what you get.