DATABASE FUNDAMENTALS
WHAT IS DATABASE MANAGEMENT
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Cardinality
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Composite entity
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Optional relationships
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Business rules
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Detailed explanation-1: -Cardinality refers to the maximum number of times an instance in one entity can relate to instances of another entity. Ordinality, on the other hand, is the minimum number of times an instance in one entity can be associated with an instance in the related entity.
Detailed explanation-2: -The cardinality of a relationship is the number of related rows for each of the two objects in the relationship. The rows are related by the expression of the relationship; this expression usually refers to the primary and foreign keys of the underlying tables.
Detailed explanation-3: -Recursive relationship: Relationship exists between occurrences of the same entity set. Binary relationship: Two entities are associated. Ternary relationship: Three entities are associated.
Detailed explanation-4: -Low cardinality refers to a database that has a lot of repeated values like status flags, Boolean values, or gender. In contrast, high cardinality refers to a database that has a large number of distinct values such as ID numbers, user names or email addresses.