Something

    def self.condition_for_find_by_udak_frag(frag, placeholder='?')
        # frag is college, department, or division
        sub_select="=#{placeholder}"
        if frag!="college"
            sub_select="IN (select id from `#{frag}s` where `name` like #{placeholder})"
        end
        return "(`units`.`#{frag}_id` #{sub_select} 
        OR `units_in_charge_faculties`.#{frag}_id #{sub_select} OR 
        (`loaned_to_unit_id` IS NOT NULL AND `loaned_to_units_rooms`.#{frag}_id  #{sub_select}))"
    end