Ch03.pdf

12/29/2016 Fundamentals of Information Systems, Seventh Edition Chapter 3 Database Systems, Data Centers, 1...

12/29/2016 Fundamentals of Information Systems, Seventh Edition Chapter 3 Database Systems, Data Centers, 1 Why Learn About Database Systems? Database: – Organized collection of data Database management system (DBMS): – Group of programs that manipulate the database – Provide an interface between the database and its users and other application programs Database administrator (DBA): – Skilled IS professional who directs all activities related to an organization’s database 2 1  12/29/2016 Data Management Without data and the ability to process it: – An organization could not successfully complete most business activities Data consists of raw facts To transform data into useful information: – It must first be organized in a meaningful way 3 The Hierarchy of Data Bit (a binary digit): – Circuit that is either on or off Byte: – Typically made up of eight bits Character: – Basic building block of information Field: – Name, number, or combination of characters that describes an aspect of a business object or activity 4 2  12/29/2016 The Hierarchy of Data (continued) Record: – Collection of related data fields File: – Collection of related records Database: – Collection of integrated and related files Hierarchy of data: – Bits, characters, fields, records, files, and databases 5 The Hierarchy of Data (continued) 6 3  12/29/2016 Data Entities, Attributes, and Keys Entity: – A person, place, or thing for which data is collected, stored, and maintained Attribute: – Characteristic of an entity Data item: – Specific value of an attribute 7 Data Entities, Attributes, and Keys (continued) 8 4  12/29/2016 Data Entities, Attributes, and Keys (continued) Key: – Field or set of fields in a record that is used to identify the record Primary key: – Field or set of fields that uniquely identifies the record 9 The Database Approach The database approach: – Traditional approach to data management: Each distinct operational system used data files dedicated to that system – Database approach to data management: Pool of related data is shared by multiple application programs 10 5  12/29/2016 The Database Approach (continued) 11 Data Centers, Data Modeling and Database Characteristics When building a database, an organization must consider: – Content: What data should be collected and at what cost? – Access: What data should be provided to which users and when? – Logical structure: How should data be arranged so that it makes sense to a given user? – Physical organization: Where should data be physically located? 12 6  12/29/2016 Data Center Climate-controlled building or set of buildings that house database servers and the systems that deliver mission-critical information and services Traditional data centers: – Consist of warehouses filled with row upon row of server racks and powerful cooling systems 13 Data Center (continued) Many organizations now use large shipping containers packed with racks of servers and cooled to easily connect and set up Businesses and technology vendors working to develop green data centers that run more efficiently and require less energy for processing and cooling Backup and security procedures for data centers can be a concern 14 7  12/29/2016 Data Modeling Data model: – Diagram of data entities and their relationships Enterprise data modeling: – Starts by investigating the general data and information needs of the organization at the strategic level Entity-relationship (ER) diagrams: – Data models that use basic graphical symbols to show the organization of and relationships between data 15 16 8  12/29/2016 The Relational Database Model Relational model: – Describes data using a standard tabular format – Each row of a table represents a data entity (record) – Columns of the table represent attributes (fields) – The domain is the range of allowable values for data attributes 17 18 9  12/29/2016 The Relational Database Model (continued) Manipulating data: – Selecting: Eliminates rows according to certain criteria – Projecting: Eliminates columns in a table – Joining: Combines two or more tables – Linking: Manipulating two or more tables that share at least one common data attribute 19 The Relational Database Model (continued) 20 10  12/29/2016 The Relational Database Model (continued) 21 The Relational Database Model (continued) Data cleanup – Process of looking for and fixing inconsistencies to ensure that data is accurate and complete – Database normalization is often used to clean up problems with data 22 11  12/29/2016 Database Management Systems Creating and implementing the right database system ensures that the database will support both business activities and goals Capabilities and types of database systems vary considerably 23 Overview of Database Types Flat file – Simple database program whose records have no relationship to one another Single user – Only one person can use the database at a time – Examples: Access, FileMaker Pro, and InfoPath Multiple users – Allow dozens or hundreds of people to access the same database system at the same time – Examples: Oracle, Microsoft, Sybase, and IBM 24 12  12/29/2016 Providing a User View Schema: – Used to describe the entire database – Can be part of the database or a separate schema file DBMS: – Can reference a schema to find where to access the requested data in relation to another piece of data 25 Creating and Modifying the Database Data definition language (DDL): – Collection of instructions and commands used to define and describe data and relationships in a specific database – Allows database’s creator to describe data and relationships that are to be contained in the schema Data dictionary: – Detailed description of all the data used in the database 26 13  12/29/2016 Creating and Modifying the Database (continued) FIGURE 3.12 Using a data definition language to define a schema 27 Creating and Modifying the Database (continued) 28 14  12/29/2016 Storing and Retrieving Data When an application program needs data it requests the data through the DBMS Concurrency control deals with the situation in which two or more users or applications need to access the same record at the same time 29 30 15  12/29/2016 Manipulating Data and Generating Reports Query by Example (QBE) is a visual approach to developing database queries or requests Data manipulation language (DML): – Commands that manipulate the data in a database 31 Manipulating Data and Generating Reports (continued) Structured query language (SQL): – Adopted by the American National Standards Institute (ANSI) as the standard query language for relational databases Once a database has been set up and loaded with data, it can produce reports, documents, and other outputs 32 16  12/29/2016 Database Administration DBA: – Works with users to decide the content of the database – Works with programmers as they build applications to ensure that their programs comply with database management system standards and conventions Data administrator: – Responsible for defining and implementing consistent principles for a variety of data issues 33 Popular Database Management Systems Popular DBMSs for end users: – Microsoft’s Access and FileMaker Pro – Number of open source DBMS including PostgreSQL, MySQL, and CouchDB 34 17  12/29/2016 Using Databases with Other Software DBMSs can act as front-end or back-end applications: – Front-end applications interact directly with people – Back-end applications interact with other programs or applications 35 Database Applications Today’s database applications manipulate the content of a database to produce useful information Common manipulations: – Searching, filtering, synthesizing, and assimilating data contained in a database using a number of database applications 36 18  12/29/2016 Summary Data is one of the most valuable resources that a firm possesses An entity is an object for which data is collected, stored, and maintained Traditional file-oriented applications are often characterized by program-data dependence The relational model places data in two- dimensional tables 37 Summary (continued) A DBMS is a group of programs used as an interface between a database and its users and other application programs DBMS basic functions include: – Providing user views – Creating and modifying the database – Storing and retrieving data – Manipulating data and generating reports 38 19