Subject FK's and NULL
Author Daniel Jimenez

This is a question for Helen, as I have been reading her Book, and I am not
sure I understand the following statement:

"...the foreign key corresponding to the old parent PK is set to null - the
dependent rows become orphans. Clearly, this action trigger can not be
applied if the foreign key column is non-nullable..." page 302

Could you please explain.

Thank you

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