Perform a find for all employees with a job title of 123 then do a constrain found set to omit those with class xyz. In a script it would look something like this of course setting the appropriate action and criteria in each step.
Perform Find [Restore]
Constrain Found Set [Restore]
You can also program the search Nick mentioned as a 2-request search rather than performing a second search to constrain the results of the first search
Find: employees who may qualify
Omit: those who already have the XYZ record in existence.
[ Keep in mind that when searching via a relationship, you need to be testing for the existance of something specific, not for a blank related record. Searching for a blank via a relationship usually returns all records in the parent table. Sometimes you have to do a omit on "≥ 0" (omit greater or equal to zero) to avoid this relationship surprize. ]
Thank you! The constraining with an Omit seems to work very well. This will be easy to roll into scripts. Next time I'll try to ask a harder question..