It would be perfectly fine to enclose D3 in DOUBLE quotes "D3", Things in double quotes will always be seen as an identifier (like table or column name) assuming that is a valid by the context, even if the contents of the double quote would otherwise not qualify. You could defensively double quote ALL such identifiers in a statement and never get an issue. The only case where they could give you a problem if you used them in a context where an identifier was not allowed, but a string was.