"Jamie Collins" wrote in
ups.com:


I made it clear: just another thought and the alarm bells, both from
within *my* head g. But if you are looking for me to research
authorities for you vbg,

The standard texts (date, pascal, etc) are full of single-column tables
so I'm not looking for anything.

You wouldn't want to do it too often, granted, but why 'never ever'?
Constraints can be dropped and redefined, data can be modified, life
goes on.

Just because they can be changed, it doesn't make it a good idea.
Building obsolescence into a data model is not clever at all.

Have a table of sex codes with a candidate key and
cascading FKs?

No question of candidate keys or cascading anything: see the example I
quoted above.

All the best


Tim F