What is the purpose of the cross-referencing design?

QUESTION: What is the purpose of the cross-referencing design?   [signinlocker] SOLUTION   The cross-referencing design is an alternative modeling approach that guarantees the absence of null values in the foreign key. It entails the creation of a relation schema to represent the relationship type....
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What is the difference between the referencing relation schema and the referenced relation schema? How are these terms incorporated into the foreign key design?

QUESTION: What is the difference between the referencing relation schema and the referenced relation schema? How are these terms incorporated into the foreign key design?   [signinlocker] SOLUTION   The parent is the referenced relation schema and the child is the referencing relation schema (i.e.,...
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What is required to map a relationship type that exhibits a 1:n cardinality ratio?

QUESTION: What is required to map a relationship type that exhibits a 1:n cardinality ratio?   [signinlocker] SOLUTION   Using the foreign key design, place the key (either the primary key or a candidate key) of the parent as a foreign key attribute of the...
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What would cause a relational schema for a database to contain more relation schemas than there are entity types?

QUESTION: What would cause a relational schema for a database to contain more relation schemas than there are entity types?   [signinlocker] SOLUTION   This is somewhat of a trick question. A relational schema has the same number of relation schemas as there are entity...
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What is a primary key? How do the properties of a primary key differ from those of a candidate key?

QUESTION: What is a primary key? How do the properties of a primary key differ from those of a candidate key?   [signinlocker] SOLUTION   A primary key is a candidate key that in addition to having the uniqueness and irreducibility properties also satisfies the...
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What is a candidate key? How does a candidate key differ from a superkey?

QUESTION: What is a candidate key? How does a candidate key differ from a superkey?   [signinlocker] SOLUTION   A candidate key is defined as a superkey with no proper subsets that are superkeys. A candidate key has two properties: the uniqueness property and the...
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What is the difference between a derived attribute and a stored attribute in terms of their representation in a relation schema?

QUESTION: What is the difference between a derived attribute and a stored attribute in terms of their representation in a relation schema?   [signinlocker] SOLUTION   Only stored attributes are captured in a relation schema. [/signinlocker]
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