Chapter 4 - Summary Accounting Information Systems PDF

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Summary

Cynthia Turner...

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Chapter 4

09/17/2016

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Database- a set of interrelated, centrally coordinated data files that are stored with as little data redundancy as possible  Consolidates records previously stored in separate files into a common pool and serves a variety of users and data processing applications 

Developed to address the proliferation of master files

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Database Management System- program that manages and controls the data and the interfaces between the data and the application programs that use the data stored in the database  

Data warehouse- one or more very large databases containing both detailed and summarized data for a number of years that is used for analysis rather than transaction processing  Updated periodically  Redundant to maximize query efficiency  

Business intelligence- analyzing large amounts of data for strategic decision making  Online analytical processing – using queries to investigate hypothesized relationships among data  Data mining- using sophisticated statistical analysis, including artificial intelligence to discover unhypothesized relationships in the data

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Advantages of database systems  Data integration- master files are combined into large pools of data that many application programs access  Data sharing- integrated data are more easily shared with authorized users  

Minimal data redundancy and data inconsistencies Data independence

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Cross functional analysis

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Database Systems

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Logical view- how people conceptually organize and understand the relationships among data items

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Physical view- the way data are physically arranged and stored in the computer system

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Schema- description of the data elements in a database, the relationships among them, and the logical model used to organize and describe the data o Conceptual-organizational wide view of the entire database o External- the individual user’s view of portions of the database, which are referred to as subscheme o Internal- low level view of the database  Describes how data are stored and accessed

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Data dictionary- information about the structure of the data base o Includes a description of each data element

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DBMS Languages o DDL- data definition language, builds the data dictionary, creates the database, describes logical views, and specifies record or field security constraints o DML- data manipulation language, changes database content, including data element creations, updates, insertions and deletions o DQL- data query language, high level English like language that contains powerful, easy to use commands that enable users to retrieve, sort, order, and display data

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Relational Databases – conceptual and external level schemas as if data are stored in two dimensional tables   Primary key- database attribute that uniquely identifies a row in a

table  Foreign key- an attribute in a table that is also a primary key in another table and is used to link the two   Basic Requirements of a Relational Database  

1) Every column in a row must be single valued 2) Primary keys cannot be null

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entity integrity rule- a non null primary key ensures that every row in a table represents something and that it can be identified

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3) Foreign keys, if not null, must have values that correspond to the value of a primary key in another table  referential integrity rule- foreign keys which link rows in one table to rows in another table must have the values that correspond to the value of a primary key in another table 

4) All nonkey attributes in a table must describe a characteristic of the object identified by the primary key  

Two approached to database design  Normalization- following relational database rules to design a relational database that is free from delete, insert, and update anomalies  Semantic data modeling- the designer uses knowledge of business processes and information needs to create a diagram that shows what to include in the database

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