http://www-128.ibm.com/developerworks/views/db2/libraryview.jsp?topic_by=All+topics&sort_order=desc&lcl_sort_order=desc&search_by=&search_flag=&type_by=Articles&start_no=1&show_abstract=true&sort_by=Date&product_by=&end_no=758&count=100&show_all=true

в том числе http://www.ibm.com/developerworks/db2/library/techarticle/dm-0504greenstein/index.html
If you're migrating to DB2 UDB from a database that supports bit and Boolean operations and functions, you may be wondering how to handle these types and functions in DB2. Our author offers a method that includes table creation with columns of the bit-like or Boolean data types using constraints or triggers, and a set of user-defined functions to support bitwise and Boolean operations that imitate bit or Boolean data type behavior.

но там, вроде, и еще что-то было.

А чем противоречат друг другу миграция с MS SQL на DB2 и написание функций на C?

А чем противоречат друг другу стремление максимально сохранить структуру базы при миграции с MS SQL на DB2 и написание функций на C?