Types of Data Integrity This section describes the rules that can be applied to table columns to enforce different types of data integrity. Null Rule A null rule is a rule defined on a single column that allows or disallows inserts or updates of rows containing a null (the absence of a value) in that column. Unique Column Values A unique value rule defined on a column (or set of columns) allows the insert or update of a row only if it contains a unique value in that column (or set of columns)
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The Evolution of Data Models The quest for better data management has led to different models that attempt to resolve the file system’s critical shortcomings. Because each data model evolved from its predecessors‚ it is essential to examine the major data models in roughly chronological order. 1.1 The Hierarchical Model A Hierarchical Database Model is a data model in which the data is organized into a tree-like structure. The structure allows representing information using parent/child relationships:
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Data Dictionary: A software module and database containing descriptions and definitions concerning the structure‚ data elements‚interrelationships‚ and other characteristics of an organization’s databases. Data Mining: A process where data in a data warehouse is identified to discover key business trends and factors. Data Modeling: A process where the relationships between data elements are identified and defined to develop data models. Data Planning: A planning and analysis function
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A data dictionary is a file that defines the basic organization of a database. A data dictionary has a list of all files in the database‚ the number of records that are in each file‚ the names and types of each field. The data dictionary is hidden from users so that it is not accidentally destroyed. The data dictionary only keeps bookkeeping information and does not actually contain any data from the database. The database management system cannot access data from the database without a data dictionary
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Analyzing Data IT206 September 2‚ 2011 Don Shultz Analyzing Data The five basic steps that are required for analyzing data using Microsoft Access according to the article by Samuels and Wood (2007. The steps are to gather the data‚ create a database‚ edit and validate data‚ connect data files‚ and perform queries. The first step is to determine exactly what analyzes you want to perform and ensure that you gather all that is needed. Keep in mind to import into Access it has to be formatted
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already know what you’re thinking. It’s too early in the morning to be listening to speeches. What if I told you that my speech is about fame? Fortune? And endless hours of admiration? No I’m not talking about being a garbage man‚ I’m talking about modeling. (NARRATIVE) B.) Today we will learn about the job of a model. C.) I’ve been doing research on this subject for about 3 weeks so when I say I know exactly what it takes to become a model‚ I’m not playing around. D.) The three areas we will
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The Physical Data Model (PDM) describes how the information represented in the Logical Data Model is actually implemented‚ how the information-exchange requirements are implemented‚ and how the data entities and their relationships are maintained. There should be a mapping from a given Logical Data Model to the Physical Data Model if both models are used. The form of the Physical Data Model can vary greatly‚ as shown in Figure 31. For some purposes‚ an additional entity-relationship style diagram
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Managing Data Resources Case: Better data help Virgin Mobile Australia win the customer wars Virgin mobile Australia is a major player in the Australian mobile industry. It had grown aggressively by pioneering new products and services‚ including a prepaid service that did not require a contract‚ free voice mail‚ and billing all calls by second. Other operators followed suit‚ leaving Virgin Mobile Australia wondering how it could maintain its competitive lead. The answer lay in making better
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conceptual schema design. Designing of a Database is considered as a systematized process that moulds data into a structure which is similar to the underlying system of database management model. Systems of database management are categorized into three main types: hierarchical‚ relational‚ and network. Database design is a process to organize data into a form which matches the underlying data model of the database management system. There are three major types of database management systems: network
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BC - ABAP Dictionary Release 4.6C HELP.BCDWBDIC BC - ABAP Dictionary SAP AG Copyright © Copyright 2001 SAP AG. All rights reserved. No part of this publication may be reproduced or transmitted in any form or for any purpose without the express permission of SAP AG. The information contained herein may be changed without prior notice. Some software products marketed by SAP AG and its distributors contain proprietary software components of other software vendors. Microsoft ‚ WINDOWS
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