CMIS 351 Lesson 6 Study Questions

Define database management system.

A database management system (DBMS) is special software that permits an organization to centralize data, manage them efficiently, and provide access to the stored data by application programs.

Name and briefly describe the three components of a DBMS.

1)The data definition language is the formal language used by programmers to specify the content and structure of the database. 2) The data manipulation language is the language used to manipulate data in the database. It contains commands that permit end users and programming specialists to extract data from the database to satisfy information requests and develop applications. 3) The data dictionary is an automated or manual file that stores definitions of data elements and data characteristics such as usage, physical representation, ownership, authorization, and security.

List some benefits of a DBMS and the solutions it provides for the problems of a traditional file environment.

A DBMS can reduce the complexity of the information systems environment, reduce data redundancy and inconsistency, eliminate data confusion, create program-data independence, reduce program development and maintenance costs, enhance flexibility, enable the ad hoc retrieval of information, improve access and availability of information, and allow for the centralized management of data, data use, and security.

What is a data warehouse? How can it benefit organizations?

A data warehouse is a database with archival, querying, and data exploration tools (i.e., statistical tools). It is used for storing historical and current data of potential interest to managers throughout the organization and from external sources (e.g., competitor sales or market share). The data originate in many of the operational areas and are copied into the data warehouse as often as needed. The data in the warehouse are organized according to company-wide standards so that they can be used for management reporting and analysis. Data warehouses support looking at the data of the organization through many views or directions. A data warehouse allows managers to look at products by customer, by year, by salesperson, essentially different slices of the data. Normal operational databases do not permit such different views.

What is a distributed database, and what are the two main ways of distributing data?

A distributed database is one that is stored in more than one physical location. A distributed database can be partitioned or replicated. When partitioned, the database is divided, so that each remote processor has access to the data that it needs to serve its local area. These databases can be updated locally and later justified with the central database. With replication, the database is duplicated at various remote locations. Figure 6-12 in the textbook shows how a database is distributed.

What is the difference between a logical and a physical view of data?

A logical view of data is the way data are perceived by end users or business specialists. A physical view of data is the way the data are actually organized and structured on physical storage media.

Define and explain the significance of entities and attributes.

An entity is a person, place, thing, or event about which information can be obtained. An attribute is a piece of information describing a particular entity.

What is an information policy?

An information policy specifies organizational rules, policies and accountabilities for sharing, disseminating, collecting, standardizing, classifying and inventorying information.

Define business intelligence. Explain how it benefits organizations.

Business intelligence is the consolidation, analysis, and dissemination of data to help users make better business decisions. Organizations use business intelligence to collect information, develop knowledge about customers, suppliers and competitors, and change business decision-making to improve profitability.

Distinguish between data mining, text mining and Web mining.

Data mining is used to analyze data that is in a structured form (usually in databases and files). Text mining is used to analyze data in unstructured forms such as emails, memos, transcripts, etc. Web mining is used to discover and analyze information on the Web.

Why are data quality audits and data cleansing essential?

Data residing in any database that is not accurate or timely or that does not contain relevant information adds little if any value to an organization. In fact, data that does not contain these essential elements would more than likely do more harm to the organization than good. For example, the firm would not be able to provide their customers with good customer service, which would result in losing their business. Organizations need to identify and correct faulty data and establish routines to edit/update data once a database becomes operational. Analysis of the quality of the data involves doing a data quality audit. Basically, this consists of a structured survey of the accuracy and level of completeness of the data in the information system. Data cleansing consists of activities for detecting and correcting data in a database or file that are incorrect, incomplete, improperly formatted, or redundant. Data cleansing not only corrects data but also enforces consistency among different sets of data that originated in separate information systems.

List and describe each of the components in the data hierarchy.

Figure 6-1 in the textbook shows the data hierarchy. The data hierarchy includes bits, bytes, fields, records, files, and databases. Data are organized in a hierarchy that starts with the bit, which is represented by either a 0 (off) or a 1 (on). Bits can be grouped to form a byte to represent one character, number, or symbol. Bytes can be grouped to form a field, such as a name or date, and related fields can be grouped to form a record. Related records can be collected to form files, and related files can be organized into a database.

Why is file management important for overall system performance?

Information cannot be used effectively if it is stored in a disorganized, inflexible manner. Without proper file management, it may be difficult and even impossible to extract information from an automated system. Retrieving a simple report can be time consuming and costly if information is not properly managed. File management must also be flexible enough to accommodate new pieces of information or to combine different pieces of information in changing ways. When computer files are poorly managed, poor performance, high costs, and minimal flexibility will result.

What is normalization?

Normalization is the process of creating small stable data structures from complex groups of data when designing a relational database. Normalization streamlines relational database design by removing redundant data such as repeating groups and by enforcing referential integrity. A database that is not normalized will have problems with insertion, deletion, and modification.

Describe the capabilities of online analytical processing (OLAP) and data mining.

Online analytical processing and data mining enable the manipulation and analysis of large volumes of data from many perspectives; for example, sales by item, by department, by store, by region, in order to find patterns in the data. This type of pattern is difficult to find with normal database methods, which is why a data warehouse and data mining are usually parts of OLAP. Data mining uses a variety of techniques to find hidden patterns and relationships in large pools of data and infer rules from them that can be used to predict future behaviour and guide decision making.

List and describe the problems of the traditional file environment.

Problems with the traditional file environment include: 1) data redundancy and inconsistency. Data redundancy is the presence of duplicate data in multiple data files. In this situation, inconsistencies arise because the data can have different meanings in different files. 2) program-data dependence. Program-data dependence is the tight relationship between data stored in files and the specific programs required to update and maintain those files. This dependency is very inefficient, resulting in the need to make changes in many programs when a common piece of data, such as the postal code structure, changes. 3) lack of flexibility. Lack of flexibility refers to the fact that it is very difficult to create new reports from data when needed. Ad-hoc reports are impossible to generate; a new report could require several weeks of work by more than one programmer and the creation of intermediate files to combine data from disparate files. 4) poor security. Poor security results from the lack of control over the data because the data are so widespread. 5) lack of data sharing and availability. Data sharing can be virtually impossible if data are distributed in so many different files around the organization.

Describe the two principal contemporary types of databases and the advantages and disadvantages of each.

The principal types of databases discussed in the textbook are relational and object-oriented. The relational database model organizes data into two-dimensional tables. The relational model can relate any piece of information in one table to any piece of information in another table as long as the two tables share a common data element (such as an employee number). Because relational DBMS can easily combine information from different sources, they are more flexible than the other DBMS structures. Access paths to data are not pre-specified, so they can easily respond to ad-hoc inquiries with less extensive programming. The main problem with relational DBMS is poor processing efficiency. Response time can be very slow if large numbers of accesses to data are required to select, join, and extract data from tables. Developments in relational technology, such as indexing, are starting to overcome this problem. The object-oriented database model stores data and the procedures acting on the data as objects that can be automatically retrieved and shared. Object-oriented databases can store complex types of information, but are slower at processing larger numbers of transactions when compared to relational DBMS.

How can users access information from a company's internal databases through the Web?

Using Web browser software on a client PC, a user can access a corporate Web site over the Internet. The Web browser software requests data from the organization's database using HTML commands to communicate with the Web server. Because many back-end databases cannot interpret commands written in HTML, the Web server passes these requests for data to special middleware software that then translates HTML commands into SQL so that they can be processed by the DBMS working with the database. The DBMS receives the SQL requests and provides the required data. The middleware transfers information from the organization's internal database back to the Web server for delivery in the form of a Web page to the user. The software working between the Web server and the DBMS can be an application server, a custom program, or a series of software scripts.