摘要
关于时态数据库的先前工作 ,主要是建立在时态属性的时间间隔和事件的开始 /终止点都十分清楚的基础上。然而 ,在许多实际情况中 ,事件的时间界限并不十分清楚。因此 ,表示不明确时间 ,并给出处理不明确时间查询的方法 ,是对时态数据库中目前仍缺少的一个有效的扩展。讨论了时态数据库处理不明确时间存在的一些问题 ,并描述不明确时间间隔的方法。之后扩展了各种时态运算 ,并给出了与不明确时间相关的新运算符。也提出了能够处理不明确时间的查询语言扩展。在此讨论的时态查询语言对处理不明确时间间隔的扩展和丰富时态数据库的适应性有一定作用。
Previous work on temporal database has been mainly based on the assumption that the time intervals of temporal attributes and the start/finish point of events are precisely known.In many real life situations,however,the time boundary of events not be exactly known.Thus representing imprecise time and providing a way to write queries dealing with time impreciseness represents a useful extension currently lacking in existing/proposed temporal database systems.In this paper,we discuss the problem of handling time imprecise in temporal databases and present the representation of imprecise time intervals.Then we extend temporal operators and present new operators related to time impreciseness.We alse propose query language extensions that can dealing with time impreciseness.The extensions disscussed in this paper enrich the flexibility of temporal databases.
出处
《微机发展》
2002年第5期21-25,共5页
Microcomputer Development
关键词
时态查询语言
不明确时间隔
时态数据库
时态运算
temporal database
imprecise time intervals
temporal operate
temporal query language
