第3章 关系数据库模型 本章介绍以下内容： 关系模型提供数据的逻辑视图； 关系是关系模型的基本组成； 关系是由行（元组）和列（属性）组成的逻辑结构； 关系在关系 DBMS 中是以“表”形式实现的； 关系数据库的操作符、数据字典和系统目录； 关系数据库模型如何处理数据冗余； 索引及其重要性。 在第 2 章已了解到，关系数据模型的结构和数据独立性使得我们能够检查模型的逻辑 结构，而无须考虑与数据存储和检索相关的物理模型。同时，我们也了解到可以通过实体 联系图（ERD）采用图形化方式描述实体和实体之间的联系。本章将学习关系模型逻辑结 构的具体细节，以及如何运用 ERD 设计关系数据库。 本章也将学习关系数据库的基本组成——“关系”如何适应“表”的逻辑结构。同时， 也会发现关系模型简单的重要原因之一是： 表既可看作是逻辑单元，也可看作是物理单元。 还将学习到数据库中各个独立的表与表之间是如何实现关联的。 在学习了表、表的组成和表的联系后，引入表设计的基本概念。由于表是关系数据库 设计中必不可少的部分，我们将学习到设计良好的表和设计粗劣的表的特征。 最后将介绍一些基本概念，为后续章节学习做准备，包括对不同类型联系的检查以及
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REQUEST FOR PROPOSAL Design, Development and Implementation of an online workflow application for MGNREGS++ in Orissa 17-NREG-11-1016/11787 JUNE 02, 2011 PANCHAYATI RAJ DEPARTMENT (PRD), GOVERNMENT OF ORISSA Table of Contents 1 A) B) C) 2 2.1 2.2 2.3 2.4 2.5 3 4 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 5.14 5.15 5.16 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7 7.1 7.2 7.3 7.4 8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 9 9.1 9.2 Checklist ..................
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sier!™ ing Everything Ea Ma k al Edition Informatica Speci Data tegration In Learn: • What data integration is and why you should care • How data integration can help your business become more agile • Common data integration challenges and benefits • What to consider when looking for data integration tools Compliments of Brian Underdahl These materials are © 2014 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. Data Integration
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大学生创意创新创业教育与实践系列教程 Python程序设计与应用教程 目录 第1章 Python语言概述 9 1.1 Python语言简介 9 1.2 Python与C语言的异同 10 1.3 安装与配置Python环境 12 1.3.1 Windows系统平台 12 1.3.2 Linux系统平台 17 1.3.3 MAC系统平台 20 1.4 Python开发环境 23 本章小结 24 第2章 基本数据类型与变量 25 2.1 整数运算 25 2.2 浮点数算术 27 2.3 复数 29 2.4 字符串 29 2.5 类型转换 32 2.6 变量和值 32 2.7 赋值语句 34 2.7.1 变量引用 36 2.7.2 赋值 38 2.7.3 多重赋值 39 本章小结 41 习题 41 第3章 编写Python程序 43 3.1 IDLE 43 3.1.1 IDLE中编写程序 44 3.1.2 命令行运行程序 55 3.1.3
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the institute of cost accountants of india(ICAI) (A Statutory body under an act of parliament) SYLLABUS 2012 STRUCTURE & contents Evaluation Synthesis ANALYSIS ANALYSIS APPLICATION APPLICATION COMPREHENSION COMPREHENSION COMPREHENSION KNOWLEDGE KNOWLEDGE KNOWLEDGE LEVEL A LEVEL B LEVEL C FOUNDATION COURSE - Syllabus 2012 the institute of cost accountants of india(ICAI) (A Statutory body under an act of parliament)
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Top of Form Week 2: Tables, ER Modeling, and The DBMS - Discussion |Database Table Design (graded) | |When designing database tables, the difference between a good design and a bad design can be a few seconds in response time and | |several minutes. You may think that this is not a huge difference, but imagine waiting several minutes on a web page for your results | |to load. How
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MEAP Edition Manning Early Access Program Node.js in Action version 16 Copyright 2013 Manning Publications For more information on this and other Manning titles go to www.manning.com ©Manning Publications Co. Please post comments or corrections to the Author Online forum: http://www.manning-sandbox.com/forum.jspa?forumID=790 Licensed to Roger Chen brief contents PART 1: NODE FUNDAMENTALS Chapter 1: Welcome to Node.js Chapter 2: Building a multi-room chat application Chapter 3:
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SAP NetWeaver ® ™ FOR DUMmIES ‰ by Dan Woods and Jeff Word SAP NetWeaver ® ™ FOR DUMmIES ‰ by Dan Woods and Jeff Word SAP® NetWeaver™ For Dummies® Published by Wiley Publishing, Inc. 111 River Street Hoboken, NJ 07030-5774 Copyright © 2004 by Wiley Publishing, Inc., Indianapolis, Indiana Published by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval
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Introduction: The capital market is the engine of growth for an economy, and performs a crucial role in acting as an intermediary between savers and companies seeking additional financing for business expansion. Stock market is part & parcel of capital market. Contribution of any stock exchange generally leads to economic growth by increasing the funds to finance industry and other enterprise. Stock Exchange is an autonomous body formed by shareholders/members. It can take various decisions independently
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Introduction: The capital market is the engine of growth for an economy, and performs a crucial role in acting as an intermediary between savers and companies seeking additional financing for business expansion. Stock market is part & parcel of capital market. Contribution of any stock exchange generally leads to economic growth by increasing the funds to finance industry and other enterprise. Stock Exchange is an autonomous body formed by shareholders/members. It can take various decisions
Words: 16966 - Pages: 68
