CORRESPONDING and ANSI SQL

Lukas Eder looks at a rarely-implemented keyword in SQL:

I recently stumbled upon a standard SQL feature that was implemented, to my surprise, in HSQLDB. The keyword is CORRESPONDING, and it can be used with all set operations, including UNION, INTERSECT, and EXCEPT.

Click through to see what it does. Be sure to check out the comments, where Joe Celko pops in to provide some additional historical context to explain why you won’t find this keyword in many implementations of the standard..