Sounds like you want to perform a kind of PIVOT operation here.
What is the purpose (application wise) of this information duplication? Effectively you are going to store the same information multiple times here - what's the added value?
Wouldn't a SELECT on the original table be sufficient instead? Building a static transpose-view is rather simple.
Using triggers is the wrong solution in most cases. It hides data design and transformation logic behind a DML operation.
- Lars