基于Asp.net的通用数据填报系统的设计与实现

本文结合实际应用,详细阐述了一种基于Asp.net的通用数据填报系统的设计与实现。该系统能够对数据表字段进行任意定义,并动态生成相应数据存储、Excel模板及界面程序,从而更灵活的进行数据填报、查询和导出。解决了传统管理信息系统扩展性差的问题,具有一定的先进性、实用性。     

模糊匹配在高校毕业生供需管理中的应用

将模糊匹配的方法与技术应用于计算机化的高校毕业生就业供需管理系统，实现毕业分配工作中学生和用人单位的双向选择，收到了良好的应用效果。     

基于MPB-Tree索引的空间数据多关键词模糊查询算法研究

随着具有定位功能的智能设备的大量使用,产生出海量的空间数据,每条数据中包含的信息越来越多,而以往的查询算法多数仅对单个关键词进行查询,已难以满足用户更为个性化的需求.为此,本文提出一种多空间关键词模糊查询算法,在该算法中,将以往的两维空间距离计算转化为莫顿码匹配提升查询效率,且与模糊查询算法融合支持查询的容错.实验结果表明,该算法的效率及准确性较以往查询算法有较大提高.     

数据库多重条件查询的方法探讨

从实用的角度出发,讨论了利用VB6．0的ADO技术及SQL语句实现对数据库的多重条件组合查询的技巧和方法,其关键在于获取标准SQL语句中的查询字符串．由于模块具有通用性,因此可以缩短程序开发周期．     

基于B~+树的索引字段加密

针对索引字段加密难的问题,提出一种基于B~+树的索引字段加密处理技术.该技术采用DBMS内部加密机制,选取在页/段映射到块时使用加密组件对索引字段进行加密,它能够使加密后的索引仍然保持有序,不会失去索引的快速查询功能.为了进一步保证索引字段本身的安全性,对索引按结点实施加密.实验中,模拟Postgresql中B~+树的构造方法,研究基于B~+树的加密索引字段的查询性能,并在页结点数和B~+树深度参数变化时,对分结点加密的查询性能进行测试.研究结果表明:基于B~+树的索引字段加密的查询速度虽然比明文查询速度下降20%左右,但采用分结点加密方式能够有效地减少解密代价,避免索引字段加密对查询性能产生较大影响.     

海量数据下的Web分页呈现研究

在Internet上经常遇到海量数据库分页呈现问题,针对ADO(AxtiveX Data Object)记录集分页、转储记录集分页和基于SQL(Structured Query Language)分页等算法在海量数据下存在响应速度慢、响应能力弱、资源占用多等缺陷,在分析这些方法的基础上,提出了一种改进的方法.该方法在传统的C/S(Client/Server)结构中将Server端的海量数据以分页的方式在Client端Web呈现给用户,然后,对所有的方法进行测试和分析,通过对比表明,新算法的响应速度最大可提高21.4%,响应能力比其他算法提高1.3～4倍,在大数据量下尤其明显.     

A solution of spatial query processing and query optimization for spatial databases

Recently,attention has been focused on spatial query language which is used to query spatial databases. A design of spatial query language has been presented in this paper by extending the standard relational database query language SQL. It recognizes the significantly different requirements of spatial data handling and overcomes the inherent problems of the application of conventional database query languages. This design is based on an extended spatial data model,including the spatial data types and the spatial operators on them. The processing and optimization of spatial queries have also been discussed in this design. In the end,an implementation of this design is given in a spatial query subsystem.     

最长公共子串的快速搜索算法

本文提出了两个字符串之间最长公共子串这一概念,并在对它进行理论分析的基础上,给出了两种求取最长公共子串的快速算法。     

分布式数据库中关系运算结果大小的估计

本文在分析了原有的几种估计关系运算结果大小的方法的基础上,提出了一新的估计模型——UDB,并对其建造方法、使用方法、适用情况及估计精度做了较详细的讨论。     

Efficient and power-awareness query over sensor networks

Sensor networks consisted of low-cost, low-power, muhifunctional miniature sensor devices have played an important role in our daily life. Light and humidity monitoring, seismic and animal activity detection, environment and habitat monitoring are the most common applications. However, due to the limited power supply, ordinary query methods and algorithms can not be applied on sensor networks. Queries over sensor networks should be power-aware to guarantee the maximum power savings. The minimal power consumption by avoiding the expensive communication of the redundant sensor nodes is concentrated on. A lot of work have been done to reduce the participated nodes, but none of them have considered the overlapping minimum bounded rectangle （MBR） of sensors which make them impossible to reach the optimization solution. The proposed OMSI-tree and OMR algorithm can efficiently solve this problem by executing a given query only on the sensors involved. Experiments show that there is an obvious improvement compared with TinyDB and other spatial index, adopting the proposed schema and algorithm.