Case insensitive in XPath constraint

Hi guys n gals,

I'm looking for a way to make my XPath constraint case insensitive.

My client can search for addresses, and I do a database lookup based on that search criteria. However, my database holds the records in the current way:

'Willem de Zwijgerweg'

my client will search for ANY combination possible: willem de zwijgerweg, Willem De Zwijgerweg, Willem de zwijgerweg etc.

Obviously the current way doesn't work.

Is there any way to make the XPAth constraint case-insensitive, or do I need to build my retrieve differently?

Thanks in advance