This Rails gem adds two methods to the ActiveRecord::Base class that allow you to update many records on a single database hit, using a case sql statement for it. Before version 0.1.3 update_by_case
gem used custom sql strings, and it was not sanitized, making it vulnerable to sql injection. Upgrade to version >= 0.1.3 that uses Arel
instead to construct the resulting sql statement, with sanitized sql.