共查询到19条相似文献，搜索用时 0 毫秒
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数据库查询是数据库的核心操作,本文详细介绍数据库系统中模糊查询技术和数据库查询优化技术的方法与技巧,提供了能实现真正模糊查询的二个通用函数的源程序,查询语言SELECT-SQL通配符的使用方法,以及查询优化中几种方法和技巧。 相似文献
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浅谈数据库数据的复杂查询利用工具的进行 总被引：1，自引：0，他引：1
数据库应用系统中数据的复杂查询问题,长期困扰着使用者和开发者。本文通过具体问题,论述了实现复杂查询的方法,同时论证了几种方法的特点及适用范围。 相似文献
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提出了一种面向对象的Web查询语言，介绍了其数据模型及查询表示，并以网上求职为例说明其实现过程。 相似文献
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软件重用的关键是能否为软件开发人员提供较好的查询支持环境，能否根据重要需求在库中定位合适的可重用软件对象。针对在对象库中查询可重用对象问题，介绍几种常见的对象库查询机制，并简要分析各种查询方法的特点。本文主要介绍在设计对象库查询工具时可采用的技术性支持方法，研究环境是一种基于对象的软件开发环境。 相似文献
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介绍了一种基于面向对象方法的系统分析设计思想在工资查询系统设计中的应用,并利用存储过程技术实现了一种可以自由定义并可随时修改工资结构的网上工资查询系统. 相似文献
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AJAX是一种新兴的web技术,它能够成功实现无刷新页面和数据的异步交互。介绍了Ajax技术的工作原理并给出了基于Java的无刷新查询的实现方法。 相似文献
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随着计算机技术越来越普及.广泛地应用于各个领域,数据库技术与应用的结合越来越紧密.数据库管理系统作为一个高级的系统软件,涉及到查询处理、并发控制、故障恢复等重要技术.本文对倚单的SOL查询.给出几个方法.使初学者轻松学会使用SOL实现查询. 相似文献
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阐述了高速铁路查询应答器系统工作原理,提出了查询天线的设计指标和设计过程,包括天线的分析、加载电阻、电容调节和匹配电路的优化仿真。通过不断的软件仿真和实验调整测试,采用一种新型的匹配电路结构实现了天线的双频工作。在设计频率范围内满足驻波要求,同时和应答器天线之间的传输性能好,可以应用于查询应答器系统。 相似文献
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作为数据的承载平台,数据库在各行各业都得到了广泛应用。查询操作是数据库管理系统最重要的功能之一,使用频率最高。以关系型数据库为基础,从不同的角度出发,对数据库查询优化策略进行了研究。 相似文献
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Interactive query expansion (IQE) (c.f. [Efthimiadis, E. N. (1996). Query expansion. Annual Review of Information Systems and Technology, 31, 121–187]) is a potentially useful technique to help searchers formulate improved query statements, and ultimately retrieve better search results. However, IQE is seldom used in operational settings. Two possible explanations for this are that IQE is generally not integrated into searchers’ established information-seeking behaviors (e.g., examining lists of documents), and it may not be offered at a time in the search when it is needed most (i.e., during the initial query formulation). These challenges can be addressed by coupling IQE more closely with familiar search activities, rather than as a separate functionality that searchers must learn. In this article we introduce and evaluate a variant of IQE known as Real-Time Query Expansion (RTQE). As a searcher enters their query in a text box at the interface, RTQE provides a list of suggested additional query terms, in effect offering query expansion options while the query is formulated. To investigate how the technique is used – and when it may be useful – we conducted a user study comparing three search interfaces: a baseline interface with no query expansion support; an interface that provides expansion options during query entry, and a third interface that provides options after queries have been submitted to a search system. The results show that offering RTQE leads to better quality initial queries, more engagement in the search, and an increase in the uptake of query expansion. However, the results also imply that care must be taken when implementing RTQE interactively. Our findings have broad implications for how IQE should be offered, and form part of our research on the development of techniques to support the increased use of query expansion. 相似文献
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We propose a new query reformulation approach, using a set of query concepts that are introduced to precisely denote the user’s information need. Since a document collection is considered to be a domain which includes latent primitive concepts, we identify those concepts through a local pattern discovery and a global modeling using data mining techniques. For a new query, we select its most associated primitive concepts and choose the most probable interpretations as query concepts. We discuss the issue of constructing the primitive concepts from either the whole corpus or from the retrieved set of documents. Our experiments are performed on the TREC8 collection. The experimental evaluation shows that our approach is as good as current query reformulation approaches, while being particularly effective for poorly performing queries. Moreover, we find that the approach using the primitive concepts generated from the set of retrieved documents leads to the most effective performance. 相似文献
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Ruihua Song Zhenxiao Luo Jian-Yun Nie Yong Yu Hsiao-Wuen Hon 《Information processing & management》2009
It is widely believed that many queries submitted to search engines are inherently ambiguous (e.g., java and apple). However, few studies have tried to classify queries based on ambiguity and to answer “what the proportion of ambiguous queries is”. This paper deals with these issues. First, we clarify the definition of ambiguous queries by constructing the taxonomy of queries from being ambiguous to specific. Second, we ask human annotators to manually classify queries. From manually labeled results, we observe that query ambiguity is to some extent predictable. Third, we propose a supervised learning approach to automatically identify ambiguous queries. Experimental results show that we can correctly identify 87% of labeled queries with the approach. Finally, by using our approach, we estimate that about 16% of queries in a real search log are ambiguous. 相似文献
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Although most of the queries submitted to search engines are composed of a few keywords and have a length that ranges from three to six words, more than 15% of the total volume of the queries are verbose, introduce ambiguity and cause topic drifts. We consider verbosity a different property of queries from length since a verbose query is not necessarily long, it might be succinct and a short query might be verbose. This paper proposes a methodology to automatically detect verbose queries and conditionally modify queries. The methodology proposed in this paper exploits state-of-the-art classification algorithms, combines concepts from a large linguistic database and uses a topic gisting algorithm we designed for verbose query modification purposes. Our experimental results have been obtained using the TREC Robust track collection, thirty topics classified by difficulty degree, four queries per topic classified by verbosity and length, and human assessment of query verbosity. Our results suggest that the methodology for query modification conditioned to query verbosity detection and topic gisting is significantly effective and that query modification should be refined when topic difficulty and query verbosity are considered since these two properties interact and query verbosity is not straightforwardly related to query length. 相似文献
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This paper examines the factors affecting the performance of global query expansion based on term co-occurrence data and suggests a way to maximize the retrieval effectiveness. Major parameters to be optimized through experiments are term similarity measure and the weighting scheme of additional terms. The evaluation of four similarity measures tested in query expansion reveal that mutual information and Yule's Y, which emphasize low frequency terms, achieve better performance than cosine and Jaccard coefficients that have the reverse tendency. In the evaluation of three weighting schemes, similarity weight performs well only with short queries, whereas fixed weights of approximately 0.5 and similarity rank weights were effective with queries of any length. Furthermore, the optimal similarity rank weight achieving the best overall performance seems to be the least affected by test collections and the number of additional terms. For the efficiency of retrieval, the number of additional terms needs not exceed 70 in our test collections, but the optimal number may vary according to the characteristics of the similarity measure employed. 相似文献
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This paper describes the development and testing of a novel Automatic Search Query Enhancement (ASQE) algorithm, the Wikipedia N Sub-state Algorithm (WNSSA), which utilises Wikipedia as the sole data source for prior knowledge. This algorithm is built upon the concept of iterative states and sub-states, harnessing the power of Wikipedia’s data set and link information to identify and utilise reoccurring terms to aid term selection and weighting during enhancement. This algorithm is designed to prevent query drift by making callbacks to the user’s original search intent by persisting the original query between internal states with additional selected enhancement terms. The developed algorithm has shown to improve both short and long queries by providing a better understanding of the query and available data. The proposed algorithm was compared against five existing ASQE algorithms that utilise Wikipedia as the sole data source, showing an average Mean Average Precision (MAP) improvement of 0.273 over the tested existing ASQE algorithms. 相似文献
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针对目前网上文献查询遇到的问题，本文探讨把多个分散的文献数据库联合起来，构建一个分布式文献数据库查询系统。经分析，该系统能够大大减少用户的通讯代价和数据处理时间，而且，把查询数据存储起来．，建立自身的查询记录数据库，能够进一步减少查询代价。该系统构建简单，具有应用与推广意义。 相似文献