标准数据库技术词汇之ISO/IEC 9075-2（2）

前言
ISO/IEC 2382（1）
ISO/IEC 2382（2）
ISO/IEC 2382（3）
ISO/IEC 2382（4）
ISO/IEC 2382（5）
ISO/IEC 2382（6）
ISO/IEC 2382（7）
ISO/IEC 2382（8）
ISO/IEC 2382（9）
ISO/IEC 2382（10）
ISO/IEC 2382（11）
ISO/IEC 2382（12）
ISO/IEC 2382（13）
ISO/IEC 9075-1（1）
ISO/IEC 9075-1（2）
ISO/IEC 9075-1（3）
ISO/IEC 9075-2（1）

ISO/IEC 9075-2（2）

Coordinated Universal Time (UTC)
UTC
Coordinated Universal Time
time scale (3.1.1.5) with the same rate as International Atomic Time (TAI), but differing from TAI only by an integral number of seconds (3.1.2.1)
Note 1 to entry: UTC is the time standard commonly used across the world from which local time is derived.
Note 2 to entry: UTC is produced by the Bureau International des Poids et Mesures (BIPM), i.e. the International Bureau of Weights and Measures.
Note 3 to entry: TAI is a continuous time scale produced by the BIPM based on the best realizations of the SI second. TAI is a realization of Terrestrial Time (TT) with the same rate as that of TT, as defined by the International Astronomical Union Resolution B1.9 (2000).
协调世界时
UTC
与国际原子时（TAI）具有相同速率的时间标度，但与TAI的差异仅在于整数秒数
注1：UTC是世界各地通用的时间标准，从中得出本地时间。
注2：UTC由国际计量局（BIPM）产生 。
【译注：未提供此术语定义的文字描述，而是“取自”ISO 8601。对应ISO 8601-1 3.1.1.12。】

date
time (3.1.1.2) on the calendar (3.1.1.18)time scale (3.1.1.5)
Note 1 to entry: Common forms of date include calendar date (3.1.2.7), ordinal date (3.1.2.8) or week date (3.1.2.9).
日期
日历时间标度上的时间
注：常用日期形式包括日历日期、序数日期或星期日期。
【译注：未提供此术语定义的文字描述，而是“取自”ISO 8601。对应ISO 8601-1 3.1.1.1。】

assignable (of data types)
characteristic of a data type T1 that permits a value of T1 to be assigned to a site of a specified data type T2, where T1 and T2 may be the same data type
（数据类型）可指定的
数据类型T1的 特性，允许将T1的值指定给规定的数据类型T2的场所，此处的T1和T2可能是同一数据类型

assignment
operation whose effect is to ensure that the value at a site T (known as the target) is identical to be a given value S (known as the source)
Note 1 to entry: Assignment is frequently indicated by the use of the phrase “T is set to S” or “the value of T is set to S”.
指定
操作，其效果是确保站点T处的值 （称为目标）与给定值S（称为源）相同
注：常使用短语“将T设置为S”或“将T的值设置为S”来表明指定 。

attribute
component of a structured type
Note 1 to entry: Each value V in structured type T has exactly one attribute value for each attribute A of T. The characteristics of an attribute are specified by an attribute descriptor. The value of an attribute may be retrieved as the result of the invocation A(V) of the observer function for that attribute.
属性
结构类型的组件
注：结构类型T中的每一值V，对于T的每一属性A都只有一个属性值。属性的特性由属性描述符规定。可以将属性值作为对该属性的观察函数调用 A(V) 的结果来检索。
【译注：ISO/IEC 2382已有此术语定义。】

cardinality (of a collection)
number of elements in that collection
Note 1 to entry: Those elements need not necessarily have distinct values. The objects to which this concept applies include tables and the values of collection types.
（汇集的）势（基数）
汇集中的元素数
注： 那些元素不必有相异的值。 此概念适用的对象包括表以及汇集类型的值。

comparable (of a pair of values)
capable of being compared, according to the rules of Subclause 8.2, “”
Note 1 to entry: In most, but not all, cases, the values of a data type can be compared one with another. For the specification of comparability of individual data types, see Subclause 4.2, “Character strings”, through Subclause 4.10, “Collection types”.
（一对值）可比的
能进行比较
注：在大多数情况下，但不是所有情况下，数据类型的值可相互比较。

constructor function
niladic SQL-invoked function of which exactly one is implicitly specified for every structured type
Note 1 to entry: An invocation of the constructor function for data type T returns a value V of the most specific type of T such that V is not the null value and, for every observer function O defined for T, the invocation O(V) returns the default value of the attribute corresponding to O.
构造函数
无参的 SQL调用函数， 隐式地为每个结构类型只规定一个构造函数
注：调用数据类型T的构造函数，返回T的最特定类型的值V，使得V不是空值，且对于为T定义的每个观察函数O，调用O(V) 都返回对应于O的默认属性值。

data model (general)
definition of the kinds of data that belong to a particular universe of discourse, including the operations on those kinds of data
（通用） 数据模型
属于特定论域的多种数据的定义，包括对那些种数据的操作

declared type (of an expression denoting a value or anything that can be referenced to denote a value, such as, for example, a parameter, column, or variable)
unique data type that is common to every value that might result from evaluation of that expression
（ 表达式的） 声明类型
对于每个值共同的唯一数据类型 ，可能是计算表达式产生的值