Given the number of times I need to do this I've decided to go down the hash route . However thanks for your answer, it's shown me some things I hadn't considered (even after reading the manual).
One thing I'd like to add is that the " around the SQL statement is purely habit on my part.
I often have to write SQL that does something like this
"select blah from v\$someview where upper(NAME) like upper('%file%')"
Hence the need to use double instead of single quotes