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When a foreign key field is left empty, that implies that no foreign key relationship was claimed. By definition a primary key cannot be no. But a foreign key,
by tyronehed 2y ago
When a foreign key field is left empty, that implies that no foreign key relationship was claimed. By definition a primary key cannot be no. But a foreign key, which is a representation of another table's primary key, can be null. It merely means that no foreign key relationship is claimed.