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Datalog. I honestly love SQL...I consider it a noble language:) It is the only declarative language out there that is still used today, and there are some soli

Datalog. I honestly love SQL...I consider it a noble language:) It is the only declarative language out there that is still used today, and there are some solid reasons for that. However, I believe the biggest mistake that was made in the creation of SQL was to try to emulate natural language flow patterns. This makes it hard to format and edit, and when people optimize towards writability, they kill readability (such as the use of leading commas. The lack of any real standard indentation practice makes it cooperative work frustrating. And the natural language flow actually confuses the writer/reader into thinking that order of operations is linear, as opposed to the FROM->WHERE->GROUP BY->HAVING->SELECT->ORDER BY->LIMIT order. This makes for really annoying logical bugs, such as how filter conditions in the where clause on a left-joined table can effectively turn your left join into an inner join.

einhverfr 13y ago
The biggest mistake in SQL was in using NULLs to mean three different things (no record found in an outer join, vs not applicable, vs not yet known). Fortunately with some types (varchar) on sane db's you can use dedicated empty values ('' for varchar) for not applicable, but you are still stuck with the other two as possibly conflicting. This is actually a big issue because your ability to have complex declarative constraints goes up with table width, so breaking off potentially nullable columns also removes them from being available for cross-column check constraints.