Answer
Cardinality can describe the number of rows in a relation or the relationship multiplicity between entities. • Query optimizers estimate row cardinalities to compare plans. • Data modeling uses terms such as one-to-one and one-to-many. • The intended meaning should be stated because the term is context-dependent.
💡 SQL Example
SELECT COUNT(*) FROM employees;
Result
The table row cardinality
⚡ Quick Revision
Cardinality describes row count or relationship multiplicity, depending on context.