anti-join with SQL::Statement?

  Dear fellow DBI users,

Recently I discovered (by asking on #perl, as usual) that SQL::Statement
supports joins.  I like this, because it allows me to compute the
relational join of two CSV tables and store the result as a new CSV table.

Actually, I'd like to apply *all* relational algebra operations.
So the next thing I tried was the anti-join (see

  http://en.wikipedia.org/wiki/Relational_algebra#Antijoin

) and here I failed: it does not appear to be supported.
SQL offers various ways to express it, but none of them I can think
of are supported in SQL::Statement:

 - no EXCEPT (or UNION, for that matter)
 - no NOT IN (or nested selects in general)
 - no functions as column specifiers (to be exact: only in the parser)

Although I developed a workaround (and #perl told me it was probably
the best I could do) this left me with two questions:

 + Have I overlooked a way of expressing the anti-join in SQL::Statement?

 + Is there any interest (besides my own) in adding such functionality
   to SQL::Statement if it isn't there?

-- 
Reinier Post
TU Eindhoven