Cardinality

Cardinality refers to the number of tuples (rows) in a relation (table) in a database. It represents the size or extent of a relation and provides information about the number of records or instances in a table.

Explanation:

When designing a database, it is important to determine the cardinality of the relationships between entities. Cardinality can be classified as one-to-one, one-to-many, or many-to-many.

- One-to-one: In a one-to-one relationship, each record in one table is associated with only one record in another table. For example, in a database that stores employee information, each employee may have only one unique employee ID, and this employee ID is linked to a single record in the employee table.

- One-to-many: In a one-to-many relationship, a record in one table can be associated with one or more records in another table. For example, in a database that stores customer and order information, a customer can have multiple orders, but each order is associated with only one customer.

- Many-to-many: In a many-to-many relationship, records in one table can be associated with multiple records in another table, and vice versa. For example, in a database that stores student and course information, a student can enroll in multiple courses, and each course can have multiple students.

In all these cases, the cardinality of the relationships determines how the tables are connected and how the data is organized. It helps to establish the structure and integrity of the database.

Conclusion:

In the given options, the term that refers to the number of tuples in a relation is cardinality. It is an important concept in database management systems and helps in understanding the size and relationships between tables.