Create a new field that is a calculation:
If (field A = field B ; 1 ; 0 )
Put the new field on your layout and search for any records that have a 1 in that field.
Actually, you can just do
field A = field B
You'll already get a 1 if true, and a zero if false. May want to uncheck the box that says "do not evaluate if all referenced fields are empty", though, if you want blank=blank to be "true" (1).
The implicit Boolean is cool. But I tend to favor explicit coding, just for the sake of the poor slob coming behind me who doesn't know about implicit.
ditto. or me looking at something I did, but a few years later.... saves me from many "what-the" moments.
Thanks for your responses, but they depend on having developer access. I take it from your suggestions that it is not possible for a user with access only to a layout to do such a find using the standard controls? I know I could develop a query layout that tries to anticipate all the kinds of search a user might want but there's always someone wanting something different.
short answer: No
not in Find-mode, not without helper fields, not without coding
we are using 'dashboard' layouts, where we let users search/select some addresses (for example) via a scripted SQL query and show the found set in a virtual list. That's quite fast with a relatively small selection, even over WAN. SQL has more potential than the native FileMaker 'Find' mode (with some draw-backs as well). Although we don't need to calculate in our queries, it should be possible using SQL