基于字符串解析的智能查询方法及其应用

大多数数据库应用程序的查询统计功能是事先按照用户的需求定制的,动态查询功能非常有限．针对此类问题,根据一条合法的不确定的SQL语句,应用字符串解析技术,提出一种通用的智能查询方法．该方法可动态计算出SQL语句中所有字段名、字段别名及相应的字段类型,并据此生成一个自适应的查询界面;然后在用户设置查询条件后自动合成为一条新的SQL语句;并将由此SQL语句得到的结果显示在一个统一的查询统计窗口上;最后以引航调度系统为例,用Delphi7和oracle9i实现智能查询统计功能并给出相应源码．实践表明,该方法是十分有效的,实现的代码是可重复使用的．     

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．     

多租户宽表数据存储模式的查询重写机制研究

在SaaS环境下,基于宽表(Universal Table)的多租户数据存储模式是有效解决多租户数据存储问题的一种方法,但会产生大量模式空值。为此,提出了多宽表的存储模式,实现了基于Java的动态SQL重写和视图定义SQL重写相结合的查询重写方法,通过判断SQL语句的复杂性选择适当的查询重写方法,保证租户视图层的SQL查询可转换为实际作用于数据库的SQL查询。分析证明多宽表模式可以提高存储空间利用率,并通过实验验证了该方法查询重写的可行性。     

B/S模式下查询方法性能分析

在B/S模式下,通常Web利用动态SQL语句或存储过程查询数据 库,本文对使用动态SQL语句和存储过程进行测试和比较,分析使用这两种方法的查询效率 及对Web服务器和数据库服务器负载的影响,对实际工程设计具有一定的参考价值.     

DFMapper:基于查询树的SQL-to-HiveQL自动翻译工具

Hive作为建立在Hadoop上的数据仓库,已成为很多企业处理大数据的首选。然而,传统企业中大量的遗留应用依赖于传统关系型数据库(RDBMS),迁移时需要翻译大量查询语句。提出了一种基于查询树的SQL到HiveQL的自动翻译方法。该方法利用SQL解析器将SQL语句解析为查询树,提供8种不同的重写策略重构查询树,进而将其转化为正确的HiveQL语句,实现了一个翻译工具——DFMapper。在基准测试集TPC-DS上进行的查询实验证明,DFMapper可以正确翻译绝大多数的查询语句,并且具有很强的扩展性。     

浅谈T-SQL语言之递归查询

文章以T-SQL技术为基础,介绍了基于CTE语句进行数据库查询的产生机理和实现方法,并针对CTE语句的特点,采用存储过程及自定义函数方式来实现基于CTE语句查询数据库的过程.以人员管理树型结构数据为基础,在SQL Server 2005中建立各种CTE临时结果集,进行递归查询操作,从而体现T-SQL语言中新增CTE递归查询的强大功能.     

关系数据库细粒度访问控制设计与实现

通过扩展SQL语句支持关系数据库细粒度访问控制(FGAC)策略的描述,扩展的SQL语句同时支持封闭式细粒度访问控制策略和开放式细粒度访问控制策略的描述,即支持细粒度的否定授权.给出了基于查询改写思想的动态查询改写算法,实现了细粒度访问控制,同时给出了细粒度访问控制实现框架,并在数据库管理系统(DBMS)中实现.实验验证了该实现方法的可行性.     

一种基于SQL语句的ID3改进算法

ID3算法沿用的是机器学习算法,与数据库集成性差。提出一种基于SQL语句的ID3改进算法。通过SQL语句直接对保存在数据库中的数据表进行分组查询,计算测试属性的条件熵,并给出深度优先和广度优先生成子树的递归算法。实验证明,改进的ID3算法充分利用了SQL的高效性和C++语言的灵活性,降低了算法实现难度,高效实现大量数据的分类。     

基于ALPHA语言的复杂查询SQL语句生成

用SQL语言表达复杂查询,是数据库教学中的一个重点和难点,但对数据库理论的初学者是个挑战。文章提出了一个复杂查询的SQL语句生成框架,首先将复杂查询用ALPHA语言表示,然后利用逻辑谓词等价变换理论,将ALPHA语句中的全称量词和逻辑蕴含进行等价变换,再使用ALPHA语言向SQL语言变换生成算法生成SQL查询。该框架在多年的教学实践中得到了检验,并取得了较好的教学效果。     

一种面向对象的Java Bean查询方法的实现

为了克服在Java Bean方法中编写许多SQL语句实现数据查询的缺点，通过查询条件进行了对象化的封装，提出了一种针对Java Bean的面向对象的查询方法．通过设置查询条件对象，使用文中所提出的查询方法能方便地实现不同条件的数据查询，可以有效地提高系统的开发效率．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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