To understand databases, it is useful to remember that the elements of data that make up the database are divided into hierarchical levels. These logical data elements make up the foundation data concepts upon which a database is built. Character . The most basic logical element is the character, which consists of a single alphabetic, numeric, or other symbol. While it may take several bits or bytes to represent a character digitally, remember that these refer to physical storage, not the logical concept of the character itself. Field . A field is a grouping of characters that represent a characteristic of a person, place, thing, or event. A person's name is typically placed in a field. A field is a data item . A data field represents an attribute or some entity . Record . A record is a collection of interrelated fields. For example, an employee's payroll record usually contains several fields, such as their name, social security number, department, and salary. Records may be fixed-length or variable-length. File . A file is a collection of interrelated records. For example, a payroll file might contain all of the payroll files for all the employees of a firm. Files are usually classified by the application for which they are used. Database . A database is an integrated collection of logically interrelated records or files. For example, the personnel database of a firm might contain payroll, personnel action, and employee skills files. The data stored in a database is independent of the application programs using it and of the type of secondary storage devices on which it is stored. Teaching Tips This slide corresponds to Figure 5.2 on p. 174 and relates to material on pp. 174-175.
Under the database management approach, data records are consolidated into databases that can be accessed by many different application programs. A database management system (DBMS) is a set of computer programs that control the creation, maintenance, and use of the databases of an organization and its end users. Four major DBMS facilities include: Database Development . A DBMS allows control of development to be placed with database administrators. The administrator uses a data definition language (DDL) to develop and specify the data contents, relationships, and structure of each database, and to modify these specifications when necessary. This approach improves integrity and security for the organizational databases. The information is stored in a data dictionary, which uses data definitions to specify what all the records and files are, can be, and, if desired, to automatically enforce data element definitions when fields, records, or files are modified. Database Interrogation . A DBMS allows end users without programming skills to ask for information from a database using a query language or report generator. Queries are usually made one of two ways: SQL (Structured Query Language). This uses the basic form of SELECT ...FROM...WHERE. After SELECT the user lists the data fields to be retrieved. After FROM the user lists the files or tables from which the data must be retrieved. After WHERE the user specifies conditions that limit the search. QBE (Query by Example). This method allows users to point and click on display boxes for each of the data fields in one or more files to specify the rules of the search Database Maintenance . Updating the databases and other maintenance are conducted by transaction processing programs. Application Development . A DBMS makes application development much easier and quicker by allowing developers to include data manipulation language (DML) statements in their programs that let the DBMS perform necessary data-handling activities. Teaching Tips This slide corresponds to Figure 5.5 on p. 177 and relates to material on pp. 177-180.
Six major types of databases are illustrated on the slide and used by computer-based organizations: Operational Databases . These databases store detailed data needed to support the operations of the entire organization. They are also called subject area databases (SADB), transaction databases, and production databases. These also include databases of Internet and electronic commerce activity, such as click stream data or data describing online behavior of visitors at a company’s website. Data Warehouse Databases . These store data from current and previous years that has been extracted from the various operational and management databases of the organization. As a standardized and integrated central source of data, warehouses can be used by managers for pattern processing, where key factors and trends about operations can be identified from the historical record. Data Marts . Are subsets of the data included in a Data Warehouse which focus on specific aspects of a company, e.g. department, business process, etc. Distributed Databases . These are the databases of local workgroups and departments at regional offices, branch offices, and other work sites needed to complete the task at hand. They include relevant information from other organizational databases combined with data and information generated only at the particular site. These databases can reside on network servers, on the World Wide Web, or on Intranets and Extranets. End User Databases . These consist of a variety of data files developed by end users at their workstations. For example, an end user in sales might combine information on a customer’s order history with her own notes and impressions from face-to-face meetings to improve follow-up. External Databases . Many organizations make use of privately generated and owned online databases or data banks that specialize in a particular area of interest. Access is usually through a subscription for continuing links or a one-time fee for a specific piece of information (like the results of a single search). Other sources like those found on the Web are free. Teaching Tips This slide corresponds to Figure 5.10 on p. 181 and relates to material on pp. 180-182.
A data warehouse stores data that has been extracted from various operational, external, and other databases within the organization. To create a data warehouse, data from various databases are captured, cleaned, e.g. sorted, filtered, converted, and transformed into data that can be better used for analysis. The data is then stored in the enterprise data warehouse, from where it can be moved into data marts or to an analytical data store that holds data to support certain types of analysis. Metadata , that defines the data in the data warehouse, is stored in a Metadata Directory that is used to support data administration. A variety of analytical software tools can then be used to query, report, and analyze data. One such means for analyzing data in a data warehouse is called data mining. In data mining , the data in a data warehouse are analyzed to reveal hidden patterns and trends in historical business activity. This can help managers make decisions about strategic changes in business operations. Teaching Tips This slide corresponds to Figure 5.11 on p.182 and relates to material on pp. 182-183.
The rapid growth of websites on the Internet and corporate intranets and extranets has dramatically increased the use of databases of hypertext and hypermedia documents. Hypermedia Database : A website stores information in a hypermedia database consisting of a home page and other hyperlinked pages of multimedia or mixed media (text, graphics and photographic images, video clips, audio segments, and so on). Browser : A web browser on your client PC is used to connect with a web network server. This server runs web software to access and transfer the web pages you request. Web Site : A website uses a hypermedia database consisting of HTML (Hypertext Markup Language) pages, GIF (graphics image files) files, and video files. Web Server Software : Acts as a database management system to manage the use of the interrelated hypermedia pages of the website. Teaching Tips This slide corresponds to Figure 5.13 on p.184 and relates to material on pp. 183-184.
The security and integrity of an organization's databases are the major concerns of the data resource management efforts. Key activities of data resource management include: Database Administration . This area is responsible for developing and maintaining the organization's data dictionary, as well as designing and monitoring the performance of databases, and enforcing the standards for database use and security. Data Planning . Data planning is a corporate planning and analysis function responsible for the overall data architecture for the firm. This role ensures that data resources are developed to support the firm's strategic mission and plans. Data Administration . This area involves the establishment and enforcement of policies and procedures for managing data as a strategic corporate resource. This means standardizing data so that it is available to all end users from whatever database they are working. Teaching Tips This slide corresponds to Figure 5.14 on p.185 and relates to material on pp. 184-186.
The relationships among the records stored in databases are based upon one of several logical database structures or models. These fundamental database structures are described below. Hierarchical Structure . Under this tree-like structure, each data element is related only to one element above it, a so-called one-to-many relationship. All records are dependent and arranged in multilevel structures. Network Structure . This structure features a many-to-many arrangement whereby the DBMS can access a data element by following one of several paths. Relational Structure . This model has become the most popular structure and is used by most microcomputers. All data elements within the database are viewed as being stored in the form of simple tables. The DBMS can link data elements from various tables to provide information to end users. Teaching Tips This slide corresponds to Figure 5.16 on p. 189 and relates to material on pp. 189-190.
Object-Oriented Structure . Objects consist of data values describing the attributes of an entity and the operations that can be performed on the data. This is called encapsulation and allows object-oriented database structures to better handle complex types of data such as video and audio. The object-oriented model also supports inheritance , allowing new objects to replicate some or all the characteristics of one or more parent objects, as shown in the slide. Such capabilities allow developers to copy and combine objects, allowing for very rapid development of new database solutions. Multidimensional Structure . This structure uses cells within a multidimensional framework to aggregate data related to elements within a given dimension. Each cell combines with similar cells to form a coherent &quot;cube&quot; of information and data, which in turn is combined with other cubes to form dimensions. As a result they are both compact and easy to understand. Multidimensional structures have fast become the most popular database structure for analytical databases that support online analytical processing (OLAP) applications. Teaching Tips This slide corresponds to Figure 5.17 on p.191 and Figure 5.18 on p. 192 and relates to material on pp. 190-192.
Efficient access to data is the critical necessity of an effective database system. Key concepts and terms associated with file access include: Key Fields . This is a unique identifier of the data record. URLs . The files and databases on the Internet and corporate intranets and extranets use URLs (Uniform Resource Locators) for data access. Thus, pages of hyperlinked text and multimedia documents on the Web and intranet/extranet websites are accessed by URLs. Sequential Organization . This refers to a structure in which the records are physically stored in a specified order according to a key field in each record. Sequential Access . This refers to the predetermined order of processing data. Each record is accessed according to the same set of commands. Access begins at the start of the file or record and proceeds, in order, to the end. This is a fast and efficient method for processing large volumes of data. Direct Access . Under this method, records do not have to be arranged into any particular sequence on storage media, however the computer must keep track of the storage location of each record. Key Transformation . This common direct access technique performs an arithmetic computation on a key field or record and uses the number that results as an address to store and access that record. Indexed Sequential Access Method . This approach combines features of both sequential and direct access. Sequential storage allows for large volume processing while indexed addressing allows direct access of smaller amounts of data from individual records. Teaching Tips This slide relates to material on pp. 193-196.
Database planning, beyond that of a personal or small business end user database created by a database management package, typically requires use of a top-down data planning process based upon the systems development model covered earlier: 1. Data Planning . At this stage, planners develop a model of business processes. This results in an enterprise model of business processes with documentation. 2. Requirements Specification . This stage defines the information needs of end users in a business process. Description of needs may be provided in natural language or using the tools of a particular design methodology. 3. Conceptual Design . This stage expresses all information requirements in the form of a high-level model. 4. Logical Design . This stage translates the conceptual model into the data model of a DBMS. 5. Physical Design . This stage determines the data storage structures and access methods. Teaching Tips This slide corresponds to Figure 5.22 on p.197 and relates to material on pp. 196-198.
Fifth Edition 1 M a n a g e m e n t I n f o r m a t i o n S y ...
13 Data Resource Management
<ul><li>Explain the importance of data resource management to an organization, and how it can be implemented by database management, database administration, and data planning activities. </li></ul><ul><li>Outline the advantages of the database management approach to managing the data resources of a business. </li></ul><ul><li>Explain how database management software helps business professionals and supports business operations and management of a business. </li></ul>Chapter Objectives
<ul><li>Provide examples to illustrate each of the following concepts: </li></ul><ul><ul><li>Major types of databases </li></ul></ul><ul><ul><li>Data warehouses and data mining </li></ul></ul><ul><ul><li>Logical data elements </li></ul></ul><ul><ul><li>Fundamental database structures </li></ul></ul><ul><ul><li>Database access methods </li></ul></ul><ul><ul><li>Database development. </li></ul></ul>Chapter Objectives
Logical Data Elements Employee Record 2 Employee Record 1 Employee Record 3 Employee Record 4 Name SS Salary Name SS Salary Name SS Salary Name SS Salary Data Data Data Data Data Data Data Data Data Data Data Data Personnel Database Payroll File Benefits File
Database Management Systems Operating System Database Management System Application Programs Databases Data Dictionary Database Management <ul><li>Database Development </li></ul><ul><li>Database Interrogation </li></ul><ul><li>Database Maintenance </li></ul><ul><li>Application Development </li></ul>
Major Types of Databases Network Server External Databases on the Internet & Online Services Client PC or NC Operational Databases of the Organization Data Mart End User Databases Data Warehouse Distributed Databases on Intranets & Other Networks
Data Warehouse and Data Mining Client PC or NC Analytical Data Store Enterprise Warehouse Data Mart Data Acquisition Subsystem Warehouse Design Subsystem Data Management Subsystem Data Access and Delivery Subsystem Web Information System Operational Databases Metadata Directory Metadata Repository Metadata Management Subsystem
Web-Based Systems Web Browser Web Server Software Network Server The Internet Intranets Extranets Client PCs or NCs HTML pages GIF image files Video files Web Objects
Data Resource Management Data Administration Data Planning Database Administration
Database Structures Employee 2 A Empno Ename Etitle Dept 1 2 B 3 C Relational Structure Network Structure Hierarchical Structure Employee 3 Project B Project A Dept Dname Dloc Dmgr A B C Employee 2 Employee 1 Project A Employee 1 Dept A Dept B Dept Project B
Database Structures (cont) East West Denver Feb Actual Budget Margin Sales TV VCR TV VCR Multidimensional Database Structure <ul><li>Attributes </li></ul><ul><li>Customer </li></ul><ul><li>Balance </li></ul><ul><li>Operations </li></ul><ul><li>Deposit </li></ul><ul><li>Withdraw </li></ul>Bank Account Object <ul><li>Attributes </li></ul><ul><li>Credit Line </li></ul><ul><li>Mthly Statement </li></ul><ul><li>Operations </li></ul><ul><li>Calculate Interest </li></ul><ul><li>Print Mthly </li></ul><ul><li>Statement </li></ul>Checking Account Object <ul><li>Attributes </li></ul><ul><li>Credit Line </li></ul><ul><li>Mthly Statement </li></ul><ul><li>Operations </li></ul><ul><li>Calculate Interest </li></ul><ul><li>Print Mthly </li></ul><ul><li>Statement </li></ul>Savings Account Object Object-Oriented Database Structure
Accessing Files and Databases Key Fields Sequential Access Sequential Organization Indexed Sequential Access Method Key Transformation Direct Access URLs
Database Development User Needs Description 1. Data Planning Enterprise Model 2. Requirements Specifications 3. Conceptual Design 4. Logical Design Physical Models 5. Physical Design Data Models Logical Models
<ul><li>Data resource management is a critical management activity. Management roles include database administration, data planning, and data administration. </li></ul><ul><li>Under the database management approach, data records are consolidated into databases that can be accessed by many different application programs, serving multiple users. </li></ul>Chapter Summary
<ul><li>Database management systems are software packages that simplify the creation, use, and maintenance of databases. </li></ul><ul><li>Several types of databases are used by organizations including operational, distributed, external, data warehouses and data marts. </li></ul><ul><li>Database development for large corporate databases requires a top-down planning effort involving planning, requirements specification and logical and physical design. </li></ul>Chapter Summary (cont)