select master.*, cnt(detail.field) as cnt;
   from master;
   join detail on master.key=detail.key;
   group by master.key

Old VFP can do this, but it is out of all SQL standards.


- rewire the tables and introduce a redundant field in this table, and make sure that this field is updated whenever the number of eligible records in the detail table may change


No, Absolutely.


- write the view with an extra field without a source, and populate it manually (ok, programmatically, but that's it) on each requery


No, structureless


- try a join of the parent table with an extra view which would keep just the document key and the cnt(*) from the child table


Yes, it is the correct choice.
It is efficient and the extra view is fast and usable for other task.


- say what the hell and set engine 70


No, Standardless.


Fabio