I have two tables, for example TableA and TableB.

Each row of TableA contains a foreign key to a row of TableB.
This a 1 to 1 relation, so each row of TableA is linked to one different
row of TableB.
The foreign key field can also be NULL, in this case the TableA row is
not connected to a TableB row.

All TableB rows depend logically on TableA rows, so all TableB rows
should be linked by a TableA row.

I would like to check for program errors during development, so I would
like to know if there are "orphans" TableB rows.

May somebody suggest me a good way to find the rows in TableB that are
not connected from any row in TableA?

Thanks in advance

Fulvio Senore