The number of 'rows' in a relation is called

Question

Accepted Answer

The correct option is (3):
In the context of Relational Database Management Systems (RDBMS), a table is formally referred to as a **relation**, and a row is formally called a **tuple**. The specific term used to denote the total number of tuples or rows present in a relation is **Cardinality**. Cardinality is a fundamental property that quantifies the size of the relation vertically, indicating the number of records or data entries it currently holds. It measures the "height" of the table. As data is inserted into or deleted from the table, its cardinality increases or decreases, respectively. Therefore, the number of rows directly corresponds to the relation's cardinality.

The incorrect option is (1):
The term **Degree** does not refer to the number of rows; rather, it is the number of *attributes* or *columns* in the table. The degree of a relation represents the structure of the table, quantifying the number of fields or characteristics described by each row. You can think of the degree as measuring the "width" of the table. Unlike cardinality, the degree is a fixed structural property that only changes when the table's schema is explicitly modified to add or remove a column. Hence, it describes the structure, not the row count.

The incorrect option is (2):
The **Domain** is a concept tied to a single attribute, or column, in a relation. It is formally defined as the set of all *possible values* that a specific attribute can legally take. For instance, the domain of a 'Gender' attribute might be {'Male', 'Female', 'Other'}. It essentially specifies the allowed data type and constraints for a column to ensure data integrity and validity. It relates to the permissible values within a column, not the count of rows in the entire relation.

The incorrect option is (4):
The term **Range** is not the standard, precise terminology used in relational database theory to count the number of rows. It is a more general mathematical term. In some computing contexts, it might be loosely used to refer to a set of values or a valid interval for a variable. However, in the context of database relations, the term for the number of rows is unequivocally cardinality, making 'Range' an inappropriate and incorrect choice for this question.