Which description defines a data type?

A data type is a fundamental concept in data management that defines a collection of data values and a set of predefined operations on those values. It is essentially a classification that tells the database system how to interpret the data in a particular column or variable. For example, the INTEGER data type is a name that represents the set of whole numbers within a specific range, and it allows for arithmetic operations. This definition directly corresponds to a "named set of values."

B. A tuple is a specific data structure representing a single row in a table, not the general definition of a data type.

C. This reverses the relationship; columns are assigned a data type to constrain their values, but a data type itself does not correspond to columns.

D. This description fits a table (or relation), which has a name and contains a varying set of rows, not a data type.

1. ISO/IEC 9075-2:2016, Information technology — Database languages — SQL — Part 2: Foundation (SQL/Foundation). In Section 4.1, "Data types," the standard explicitly states: "A data type is a named set of values." This is the formal definition used in the official SQL standard.

2. Codd, E. F. (1970). A relational model of data for large shared data banks. Communications of the ACM, 13(6), 377–387. In Section 1.3, Codd introduces the concept of a "domain," the theoretical foundation for data types in relational databases, as a set of values from which an attribute can draw its actual values. This establishes the principle of a data type as a defined set of values. (https://doi.org/10.1145/362384.362685)

3. Elmasri, R., & Navathe, S. B. (2017). Fundamentals of Database Systems (7th ed.). Pearson. In Chapter 3, Section 3.1, "Domains, Attributes, Tuples, and Relations," a domain is described as having a name, data type, and format, specifying a set of atomic values. This reinforces that a data type is intrinsically linked to a named set of permissible values.