Which of the following is true about a tuple?

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BlackTom AI · Accepted Answer

Question: Which of the following is true about a tuple?

Option 1: 'It must contain a foreign key' — This is not necessarily true. A tuple is a single row of data, which may or may not include a foreign key depending on the table's design and constraints. The presence of a foreign key is not a defining characteristic of a tuple itself.

Option 2: 'It represents an instance of a table' — This statement is correct. In relational terms, a tuple corresponds to a single record (an instance) of the relation (table), containing one value for each column as defined by the schema.

Option 3: 'Its order is critical' — While a tuple has values in positions corresponding to the table's attributes, the meaningful interpretation relies on the schema's attribute order. This can be seen as true in theory, since the position of each value maps to a specific attribute. However, in many introductory explanations, emphasis is placed on the tuple representing a row rather than focusing on order as a separate property. Depending on the framing, this may be considered true or tautological, but it is not the fundamental defining statement about a tuple.

Option 4: 'It must reference another table' — This is false. A tuple does not have to reference another table; foreign keys are optional and depend on the table design. A tuple can exist in a table without any foreign key references.

Summary: The most straightforward true statement is that a tuple represents an instance (a single row) of a table, since it embodies one record across all defined attributes. The other options describe constraints or properties that are not universally required for every tuple.

Which of the following is true about a tuple?

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