信息技术 数据库语言SQL使用指南 第10部分:SQL模型（指南/模型）

[中文适用范围]： 本文件描述了在 ISO/IEC 9075-1、ISO/IEC 9075-2 和 ISO/IEC 9075-11 中定义的数据库语言 SQL 的模型。详细说明了各种概念及其关系，并通过文本和图形进行描述。文件中包含了一些历史回顾和对 SQL 关键功能的简要概述。 [外文原描述]： This document describes the model of database language SQL as defined in ISO/IEC 9075-1, ISO/IEC 9075-2, and ISO/IEC 9075-11. The meanings of and the relationships between various concepts of that model are described in text and illustrated graphically. Background in the form of some historical review and a brief overview of key SQL features is included. NOTE 2 — In spite of the fact that the names of the ISO/IEC 9075 series of standards contain the phrase “database language”, the standards do not use the word “database” to describe the thing that SQL creates and on which it operates. The word “database” is used in many different contexts and has meanings wholly unrelated to the intent of the ISO/IEC 9075 series. Consequently, a variety of other terms are defined and used by the ISO/IEC 9075 series. The word “database” is frequently used in this document informally to mean “a collection of data managed by an SQL-implementation at any given time.”