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
