What is Cardinality in Data Modeling?

Cardinality is a measure of the size of a set, often used in mathematics and computer science. It is defined as the number of elements that a set contains. For example, the set {a, b, c} has a cardinality of 3, because it contains 3 elements.

In the context of data modeling, cardinality refers to the number of records or instances of a particular entity or attribute. For example, if we have a table with five customers, each with an order, the cardinality of the "customer" entity would be 5, and the cardinality of the "order" attribute would be 5 x 4 (since each customer has four orders).

Cardinality is important in data modeling because it can help us understand the complexity of a dataset and the relationships between different entities. For example, if we have a table with a high cardinality for a particular attribute, it may indicate that there are many records with that value, and we may need to add additional attributes or tables to capture that information.