Explain i) Cardinality Ratio ii) Participation Constraint
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In a relational database, cardinality ratio refers to the number of occurrences of one entity in relation to another. It is a way of expressing the relationship between two entities in the database. For example, the cardinality ratio between a student and a class might be “one to many”, indicating that each student can be enrolled in many classes, but each class can only be enrolled in by one student.
Participation constraint, on the other hand, refers to the degree to which an entity is involved in a relationship. For example, in a database that tracks students and classes, a “total participation” constraint might be applied to the student entity, indicating that all students must be enrolled in at least one class. This means that a student cannot exist in the database unless they are enrolled in a class.
Together, cardinality ratio and participation constraint help to define the nature and extent of the relationships between entities in a relational database. This information is essential for ensuring the accuracy and integrity of the data in the database, and for enabling queries and other operations to be performed on the data.