Try something like this:

Select b.* from TableB b where not exists(select 1 from TableA a
where a.KeyField = b.KeyField)

HTH
Woody (TMW)


-----Original Message-----
From: Fulvio Senore
Sent: Friday, December 20, 2013 7:15 AM
To: firebird-support@yahoogroups.com
Subject: [firebird-support] Help with a query

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




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