One of the comments:
Cool, but it all assumes the lame way of creating SQL queries by inserting variables using string concatenation. If you have a proper SQL connector (for example Perl DBI) it supports SQL placeholders which imply handling of variable quoting by the SQL server itself, effectively preventing injections.
Response:
Interesting article, though like f055 mentioned it assumes SQL queries are done by variables through string concatenation. That does however not really imply that the universal effectiveness would be low.