Database Systems: Design, Implementation, and Management PDF

Database Systems: Design, Implementation, and Management Ninth Edition Chapter 1 Database Systems  Learning outcomes 2 In this chapter, you will learn:  The difference between data and information  What a database is, the various types of...

Database Systems: Design, Implementation, and Management Ninth Edition Chapter 1 Database Systems  Learning outcomes 2 In this chapter, you will learn:  The difference between data and information  What a database is, the various types of databases, and why they are valuable assets for decision making  The importance of database design  How modern databases evolved from file systems Database Systems, 9th Edition  Learning outcomes (cont’d.) 3  About flaws in file system data management  The main components of the database system  The main functions of a database management system (DBMS) Database Systems, 9th Edition  Introduction 4  Good decisions require good information derived from raw facts/data  Data is managed most efficiently when stored in a database  Databases evolved from computer file systems  Understanding file system characteristics is important Database Systems, 9th Edition  Why Databases? 5  Databases solve many of the problems encountered in data management  Usedin almost all modern settings involving data management: Business Research Administration  Important to understand how databases work and interact with other applications Database Systems, 9th Edition  Data vs. Information 6 Database Systems, 9th Edition  Data vs. Information 7  Data are raw facts  Information is the result of processing raw data to reveal meaning  Information requires context to reveal meaning  Raw data must be formatted for storage, processing, and presentation  Data are the foundation of information, which is the bedrock of knowledge Database Systems, 9th Edition  Data vs. Information (cont’d.) 8  Data: building blocks of information  Information produced by processing data  Information used to reveal meaning in data  Accurate, relevant, timely information is the key to good decision making  Good decision making is the key to organizational survival Database Systems, 9th Edition  Data vs. Information (cont’d.) 9  Example the photograph is information. But, what you look like is data Source: http://www.infogineering.net/data-information-knowledge.htm Database Systems, 9th Edition  Introducing the Database 10  Database: shared & integrated computer structure that stores a collection of:  End-user data: raw facts of interest to end user provided by a data warehouse or the data created by end users for query processing.  Metadata: data about data Provides description of data characteristics and relationships in data, OR Provides information about a certain item's content Complements and expands value of data Database Systems, 9th Edition  Introducing the Database 11  More on Metadata  an image may include metadata that describes how large the picture is, the color depth, the image resolution, when the image was created, and other data  A text document's metadata may contain information about how long the document is, who the author is, when the document was written, and a short summary of the document Database Systems, 9th Edition  Introducing the Database 12  More on Metadata  Web pages often include metadata in the form of meta tags. Description and keywords meta tags are commonly used to describe the Web page's content. Most search engines use this data when adding pages to their search index Database Systems, 9th Edition  Role and Advantages of the DBMS 13  Database management system (DBMS): collection of programs  Manages structure and controls access to data  DBMS is the intermediary between the user and the database  Database structure stored as file collection  Can only access files through the DBMS  DBMS enables data to be shared  DBMS integrates many users’ views of the data Database Systems, 9th Edition 14 Database Systems, 9th Edition  Role and Advantages of the DBMS (cont’d.) 15  Advantages of a DBMS:  Improved data sharing  Improved data security  Better data integration  Minimized data inconsistency  Improved data access  Improved decision making  Increased end-user productivity Database Systems, 9th Edition  Types of Databases 16  Databases can be classified according to: DB classification Users Location Usage Single-User Centralized Operational Decentralize Multiuser Warehouse d Database Systems, 9th Edition  Types of Databases 17  Users  Single-user database supports only one user at a time Desktop database: single-user; runs on PC (locally) E.g. Auto Teller Machine (ATM)  Multiuser database supports multiple users at the same time Workgroup and enterprise databases E.g. i-Student Portal, any Web application Database Systems, 9th Edition  Types of Databases (cont’d.) 18  Location  Centralized database: data located at a single site  Distributed/Decentralized database: data distributed across several different sites  Usage  Operational database: supports a company’s day-to- day operations Transactional or production database  Data warehouse: stores data used for tactical or strategic decisions Database Systems, 9th Edition  Types of Databases (cont'd.) 19  Categories of data Structured data data that is identifiable because it is organized in a structure e.g. database Semi-structured data Has structure but not enough to qualify as structured data (Loshin, 2005) e.g. XML Unstructured data No identifiable structure/in original format e.g. bitmap images/objects, text and other data types that are not part of a database Database Systems, 9th Edition  Types of Databases (cont'd.) 20  Unstructured data exist in their original state  Structured data result from formatting  Structure applied based on type of processing to be performed  Semistructured data have been processed to some extent  Extensible Markup Language (XML) represents data elements in textual format  XML database supports semistructured XML data Database Systems, 9th Edition 21 Database Systems, 9th Edition  Why Database Design Is Important 22  Database design focuses on design of database structure used for end- user data (= what?)  Designer must identify database’s expected use  Well-designed database:  Facilitates data management  Generates accurate and valuable information  Poorly designed database:  Causes difficult-to-trace errors Database Systems, 9th Edition  Evolution of File System Data Processing 23  Reasons for studying file systems/filesystems:  Complexity of database design is easier to understand  Understanding file system problems helps to avoid problems with DBMS systems  Knowledge of file system is useful for converting file system to database system  File systems typically composed of collection of file folders, each tagged and kept in cabinet  Organized by expected use Database Systems, 9th Edition  Evolution of File System Data Processing 24 Manual File Comput er File Data Systems Systems base IBM DB2/ MS EXCEL DBMS Database Systems, 9th Edition  Evolution of File System Data Processing 25 Physical Conceptual/logical Database Systems, 9th Edition  Evolution of File System Data Processing (cont'd.) 26  Contents of each file folder are logically related  Manual systems (current file systems)  Servedas a data repository for small data collections  Cumbersome for large collections  Computerized file systems  Data processing (DP) specialist (special position) converted computer file structure from manual system Wrote software that managed the data Designed the application programs to generate reports Database Systems, 9th Edition  Evolution of File System Data Processing (cont'd.) 27  Initially, computer file systems resembled manual systems  As number of files increased, file systems evolved  Each file used its own application program to store, retrieve, and modify data  Each file was owned by individual or department that commissioned its creation Database Systems, 9th Edition  Typical computer file systems 28 Database Systems, 9th Edition 29 Database Systems, 9th Edition 30 Database Systems, 9th Edition   Another example: File handling Data entry routines and reports File defination Sales files Sales Sales Salesapplication programs application programs File handling Data entry routines and reports File defination Contracts files Contracts Sales application Contracts programs application programs 31 Database Systems, 9th Edition  Problems with File System Data Processing 32  File systems were an improvement over manual system  File systems used for more than two decades  Understanding the shortcomings of file systems aids in development of modern databases  Many problems not unique to file systems  Even simple file system retrieval task required extensive programming  Ad hoc queries impossible  Changing existing structure difficult Database Systems, 9th Edition  Problems with File System Data Processing (cont'd.) 33  Security features difficult to program  Often omitted in file system environments  Summary of file system limitations:  Requires extensive programming  Cannot perform ad hoc queries  System administration is complex and difficult  Difficult to make changes to existing structures  Security features are likely to be inadequate Database Systems, 9th Edition