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What rule states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null?
Wiki User
∙ 14y ago
referential integrity constraint
Wiki User
∙ 14y ago
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Explain two rules in relational model of database systems?
1) Entity Integrity: In a base relation, no attribute of a primary key can be null. 2) Referential Integrity: If foreign key exists in a relation, either foreign key value must match a candidate key value of some tuple in its home relation or foreign key value must be wholly null
What is The relation is the set of output values for the relation?
A relation doesn't have an "output value", in the sense that a function does. A set of values is either part of the relation, or it isn't.
What relation does the cousin of your cousin have to you?
Your cousin's cousin could either be your cousin or no relation at all.
Looking for another word for available?
Another word for Available, Is either 'Online' or Open. Open as, My relation Ship status is: Open. Online as, I'm online. Available to talk. From Imogen Dodson.
What relation is your aunt's sister'husband?
Either your uncle or your father
What is the purpose of macrophage?
Macrophages primary function is to ingest foreign particles during phagocytosis either as a defence or for clean-up purposes.Macrophages also serve a role in immune response. They are able to fuse together to form a giant multinucleated cell to engulf large foreign body
What viscosity is used in the primary?
Either full synthetic or standard primary oil.
In what type of primary voters choose a candidate from either party?
Open Primary
What is aphradite to Zeus?
It is disputed, either her being his daughter, or of no relation at all.
What is your aunt's niece's relation to you?
it could either be your brother/sister or cousin
What does he mean when he says he is in relation with a girl?
Either he is related to or in a relationship with someone.
What type of primary can voters choose a candidate from either party?
closed primary
