i want the possibility to have a null value in the tCustomers.tbanksid ,
i can do it when i insert a new Customer , but the problem is that
i can't change the tCustomers.tbanksid to null to a previous inserted customer ,
this is the error message :

violation of FOREIGN KEY constraint "".
violation of FOREIGN KEY constraint "FK_TCLIENTI_1" on table "TCLIENTI".

where TClienti is tCustomer of my example

thanks for help

Maurizio

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