Re: Is this proper UNION behavior??

> Of course, the real bug here is in SQL, namely that it allows
> duplicates in tables.

Or maybe not. Tables are not *always* relations, one may have a table of
things to do. If one thing has to be done twice, it might have two entries
on the table.

It all depends on the workings of the programs using the database. Just
imagine you SELECT a subset of a tables's unique rows, but that subset
doesn't produce unique rows. Should the non-unique ones be removed behind
your back? I think not.