SQL UDF to return one column from a row

I've been going around and around on this. I've done scalar UDF's but this has me stumped.

I want to create a UDF that returns a text description from a reference file. In this case, supplier names are externally stored.

I currently do this with a join but it is a pain to repeat over & over. Also, the external file is multi-use and contains descriptions and other data for thousands of circumstances. So, this could be a big time saver for me.

example: select CompanyNbr, ItemNbr, SupplierNbr, GetSupplierName(CompanyNbr, ItemNbr, SupplierNbr) from ItemMaster

I have yet to find a decent example showing this. Does anyone have an example? Also having trouble with long name versus specific name.

Thanks!

Roger Harman
COMMON Certified Application Developer - ILE RPG on IBM i on Power