Best Way to Check Table Relationship Error

Hi all,

If I enforced a relationship between two tables in my database, say table "Customer" and "Order", it will trigger error at database layer if I try to delete a customer who has order records already without deleting them first.

What is the best and correct way to check this error and inform users that the customer cannot be deleted since it has been used in order records already? Appreciate if you can include samples/links about this.

Thanks in advance,
Garreth Goh

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