数据库的可视查询语言VQL

本文阐述数据库语言从ＱＢＥ到ＶＱＬ的发展过程，ＶＱＬ能表达ＯＯＤＢ的查询，是一个能表达否定，组合和受限全称量词的可视的数据库查询语言。     

全称量词查询的表示和实现

本文探讨了全称量词查询的实质，将全称量词查询分为比较型和存在型两种形式。文章分析了存在型量词查询的逻辑基础，介绍了嵌套定存在谓记号表示法，分组计数法和ＨＡＳＨ法。文章最后比较了不同策略的执行效率。     

发展中的SQL语言

本文回顾了ＳＱＬ语言发展的主要进程，在简要介绍了ＡＮＳＩＳＱＬ—８６后，着重分析了ＳＱＬ２对ＳＱＬ—８６，ＳＱＬ—８９所做的完善和扩展，最后就ＳＱＬ语言的未来发展ＳＱＬ３做了展望。     

基于数据库管理和存储的超文档模型

Ａｌｂｅｒｔｏ和Ｇｅｏｒｇｅ使用关系型数据库管理超文档中的链接,对查询语言ＳＱＬ进行扩展,提出查询语言ＷｅｂＳＱＬ。ＳｅｒｇｅＡｂｉｔｅｂｏｕｌ使用面向对象数据库表示超文档,对查询语言ＯＱＬ进行扩展,提出ＯＱＬ－ｄｏｃ。前者没有提出如何用数据模型表示超文档,后者则没考虑超文档中的链接,为此本文提出进一步解决方法,并以例子说明这些方法的使用。     

数据库系统与高级语言通讯

本文论述了关系数据库系统中的ＳＱＬ语言与高级语言间的通讯区的一般结构，并以ＯＲＡＣＬＥ和ＩＮＦＯＲＭＩＸ为例，对ＳＱＬＣＡ和ＳＱＬＤＡ进行了详尽的探讨。     

基于视图机制和分组统计实现 SQL 中全称量词的转换

SQL语言不支持全称量词，当查询涉及“全部”语义时，需要将全称量词等价转换为存在量词，转换及量词的使用都是难点，需要有相关的逻辑推理及思维能力，从而使程序员难以理解。基于视图机制和分组统计来实现对全称量词的对应语义的转换，思路清晰，容易掌握。     

ORACLE数据库中用户出口的开发方法

本文介绍了ＯＲＡＣＬＥＤＢＭＳ第四代语言工具ＳＱＬ＊ＦＯＲＭＳ中用户出口的概念，讨论了用ＳＱＬ＊ＦＯＲＭＳ进行数据库应用开发时使用户出口的原因及设计用户出口的一般过程和方法。     

ARTDBL-基于SQL的主动实时数据库语言

提出了一种新型的主动实时数据库语言（ＡＲＴＤＢＬ），它是传统的标准ＳＱＬ语言的扩充。讨论了ＡＲＴＤＢＬ的设计思想、功能特色和使用方式。该语言现已成功地应用到ＡＲ－ＴＤＢＳ中     

不同数据库环境中数据互用问题的探讨

重点介绍了两种典型数据库ＤＢＡＳＥ／ＦＰＸ与ＯＲＡＣＬＥ之间的数据互用技术。这种互用技术需要网络和嵌入式ＳＱＬ的支持。这一技术可在国内众多的拥有ＤＢＡＳＥ／ＦＯＸ与ＯＲＡＣＥ的用户中推广使用，其应用可大大提高工效。事实上，本文所述方法对支持ＳＱＬ语言的任何ＲＤＢＭＳ产品都是适用的。     

面向对象数据库的C宿主语言接口实现技术

面向对象的数据库管理系统（ＯＯＤＢＭＳ）通常都具备自身的查询语言，它以交互的方式供用户进行数据定义与数据操纵．除此之外，它还必须为程序员提供可在Ｃ、ＦＯＲＴＲＡＮ、ＰＡＳＣＡＬ等高级语言里嵌入使用查询语言的宿主语言接口．本文首先介绍这样一种Ｃ宿主语言接口Ｃ—ＯＳＤＬ，而后重点讨论它的实现技术，尤其是将Ｃ—ＯＳＤＬ命令转换成ＳＱＬ语句的翻译算法以及使用ＳＱＬ实现支持导航式查找的指针层次管理方法．文中讨论的Ｃ—ＯＳＤＬ实现技术以及最初的接口设计是面向对象的数据库技术的深入探讨．     

Seamlessly integrating similarity queries in SQL

Modern database applications are increasingly employing database management systems (DBMS) to store multimedia and other complex data. To adequately support the queries required to retrieve these kinds of data, the DBMS need to answer similarity queries. However, the standard structured query language (SQL) does not provide effective support for such queries. This paper proposes an extension to SQL that seamlessly integrates syntactical constructions to express similarity predicates to the existing SQL syntax and describes the implementation of a similarity retrieval engine that allows posing similarity queries using the language extension in a relational DBMS. The engine allows the evaluation of every aspect of the proposed extension, including the data definition language and data manipulation language statements, and employs metric access methods to accelerate the queries. Copyright © 2008 John Wiley & Sons, Ltd.     

基于属性相关性的SPARQL查询优化方法

目前主流的RDF存储系统都是基于关系数据库的,其查询引擎都是将SPARQL转换为SQL,然后由数据库的查询引擎来执行查询.但是,目前的数据库查询优化器对于连接查询的选择度估计都是基于属性独立假设的,这往往导致估计错误而选择了效率低的执行计划,所以属性相关性信息对于SPARQL查询优化器能否找到效率高的执行计划是非常重要的.针对SPARQL转换为SQL后,因连接操作没有优化导致查询效率不高的问题,提出了利用本体信息自动计算属性相关性的方法,从而调整连接操作的选择度估计值,调整连接顺序,提高SPARQL查询中基本图模式的连接查询效率.     

Generic multiset programming with discrimination-based joins and symbolic Cartesian products

This paper presents GMP, a library for generic, SQL-style programming with multisets. It generalizes the querying core of SQL in a number of ways: Multisets may contain elements of arbitrary first-order data types, including references (pointers), recursive data types and nested multisets; it contains an expressive embedded domain-specific language for specifying user-definable equivalence and ordering relations, extending the built-in equality and inequality predicates; it admits mapping arbitrary functions over multisets, not just projections; it supports user-defined predicates in selections; and it allows user-defined aggregation functions.     

基于SQL Server 2000的通用模糊查询工具设计

本文设计并实现了一个基于SQL Server 2000的通用模糊查询工具,该工具可以把带权重的模糊查询转换为标准的SQL语句。用户可以对SQL Server中建立的任何数据库表进行模糊查询。系统提供了以下功能：定义模糊谓词及其隶属函数;定义模糊算子;构造带权重的模糊的、精确的或混合的查询语句,权重和阈值可以由用户给出。满足查询条件的记录将根据匹配度的降序输出。本系统的设计方法也可以推广到其他的数据库系统,如Oracle,Access等。     

数据库内AI模型优化

近年来,机器学习模型在各行各业中被普遍应用.在大量变化着的数据中,数据分析师常常只关心预测结果为特定值的少量数据.然而利用机器学习模型进行推理的工作流程中,由于机器学习算法库默认数据以单表方式组织,用户必须先通过SQL语句查询出全部数据,即使随后在模型推理过程中会将大量数据丢弃.本文指出了在这个过程中,如果可以预先从模型中提取信息,就有望能在数据获取阶段快速排除不需要的数据,从而降低数据获取过程中的多表连接代价,进程间通信代价,以及模型预测代价,进而加速整个工作流程.本文以决策树模型为例,首先提出一种预筛选+验证的执行方法对查询过程进行优化,之后给出了从决策树中提取用于预筛选谓词的离线算法,最后在真实数据集上进行测试.实验结果表明,本文提出的方法能够对借助决策树模型推理结果对数据进行筛选的应用场景起到较好的加速效果.     

从SOL-92到SOL:1999

SQL plays a very important rote in the data base area,so its standardization attracts the attention of data base cooperation and the related standard organizations. Seven years later form the emer gence of SQL-92,the SQL's new version SQLt999 at last comes up at 1999. This paper describes the main contents of SQL 1999,especially the changes to SQL-92,including the new added data types,com paring predicates ,semantics ,security,trigger mechanism and other object relational characteristics,such as user defiaed structured type,stored procedure,function,method, typed relation and rets, fence type. Some under developing parts and the future works are also described.     

Spatially enabled customer segmentation using a data classification method with uncertain predicates

Spatial attributes are important factors for predicting customer behavior. However, thorough studies on this subject have never been carried out. This paper presents a new idea that incorporates spatial predicates describing the spatial relationships between customer locations and surrounding objects into customer attributes. More specifically, we developed two algorithms in order to achieve spatially enabled customer segmentation. First, a novel filtration algorithm is proposed that can select more relevant predicates from the huge amounts of spatial predicates than existing filtration algorithms. Second, since spatial predicates fundamentally involve some uncertainties, a rough set-based spatial data classification algorithm is developed to handle the uncertainties and therefore provide effective spatial data classification. A series of experiments were conducted and the results indicate that our proposed methods are superior to existing methods for data classification.     

一种基于MapReduce的OpenFlow网络属性并行验证算法

针对OpenFlow网络中流表配置错误引起转发回路、路由黑洞和访问控制规则失效等问题,提出一种并行的基于MapReduce的OpenFlow网络属性验证算法。通过在Map阶段划分规则等价类,在Reduce阶段为规则等价类构建基于交换机端口谓词的网络转发图并分析可达性,实现对网络属性的并行验证。同时,通过采用原子谓词将传统可达性分析中的规则匹配域多维集合运算转换为整数集合运算,以进一步提高可达性分析效率。此外,基于原子谓词的谓词表达方式可消除交换机端口谓词集合中的冗余项,降低存储开销。最后,通过理论分析和仿真实验验证了算法的正确性及在时间和存储开销方面的优越性。     

Spatio-temporal predicates

Investigates temporal changes of topological relationships and thereby integrates two important research areas: first, 2D topological relationships that have been investigated quite intensively, and second, the change of spatial information over time. We investigate spatio-temporal predicates, which describe developments of well-known spatial topological relationships. A framework is developed in which spatio-temporal predicates can be obtained by temporal aggregation of elementary spatial predicates and sequential composition. We compare our framework with two other possible approaches: one is based on the observation that spatio-temporal objects correspond to 3D spatial objects for which existing topological predicates can be exploited. The other approach is to consider possible transitions between spatial configurations. These considerations help to identify a canonical set of spatio-temporal predicates     

Optimization of Linear Recursive Queries in SQL

Recursion is a fundamental computation mechanism which has been incorporated into the SQL language. This work focuses on the optimization of linear recursive queries in SQL. Query optimization is studied with two important graph problems: computing the transitive closure of a graph and getting the power matrix of its adjacency matrix. We present SQL implementations for two fundamental algorithms: Seminaive and Direct. Five query optimizations are studied: 1) Storage and indexing; 2) early selection; 3) early evaluation of nonrecursive joins; 4) pushing duplicate elimination; and 5) pushing aggregation. Experiments compare both evaluation algorithms and systematically evaluate the impact of optimizations with large input tables. Optimizations are evaluated on four types of graphs: binary trees, lists, cyclic graphs, and complete graphs, going from the best to worst case. In general, Seminaive is faster than Direct, except for complete graphs. Storing and indexing rows by vertex and pushing aggregation work well on trees, lists, and cyclic graphs. Pushing duplicate elimination is essential for complete graphs, but slows computation for acyclic graphs. Early selection with equality predicates significantly accelerates computation for all types of graphs.