Agile software development emphasizes quick responses and rests on high-involvement from knowledgeable customers. A user view or external schema is also independent of database technology, but typically contains a subset of the associated conceptual schema, relevant to a particular user or group of users e.
An internal schema consists of both a physical schema and a logical schema. A logical schema consists of a representation of the data for a type of data management technology. For example, if the relational model is the technology used, then the logical schema will consist of tables, columns, rows, primary keys, foreign keys and constraints.
Three-schema architecture: a. Phases and activities of SDLC within textbook scenario: Student answers may vary depending upon whether or not they read the section closely enough to realize that Chris is following a prototyping methodology approach to developing the database application for PVFC.
The prototyping methodology is shown in Figure , while the traditional development approach is shown in Figure On the other hand, the Identify Problem phase involves sketching a preliminary data model, which is work that Chris clearly completes. Designing the Database Develop initial prototype Logical Database Design, Physical database design and definition, database implementation - Chris takes the knowledge he has gained from the initial sessions with Helen and begins to build a functioning example of the database in an agreed-upon relational database management system.
Using the Database Implement and use prototype; Revise and enhance prototype Database maintenance - Chris provided enough of a working sample database that Helen could use it and make suggestions about how to revise it.
Chris could iteratively make changes to improve the solution, and move some initial ad-hoc queries into more formal reports. Why does PVFC need a data warehouse? This database is not, however, structured in a way that supports timely analysis of trends or historical patterns. A data warehouse would enable PVFC to summarize data drawn from various operational databases i.
Online shopping sites are able to carry a large virtual inventory stored in a database for the customer to peruse.
Examples of relationships: Advanced data types have several special requirements: a. Storage requirements — multimedia objects such as images, sound, and video clips require substantial storage capacity, which needs to be justified. Content management — this is the problem of storing, locating, and retrieving the multimedia objects. This process requires specialized software not generally available in a relational DBMS or extra effort to create a means to rapidly access multimedia objects such as keyword indexes.
Maintenance — while conventional relational data are easily updated, multimedia objects may require maintaining multiple versions of the data. Usually the whole object needs to be restored because it is treated as a whole rather than a set of parts. Metadata for Class Roster: Please note that some columns have been omitted in order to save space. Why do organizations create multiple databases? There are several reasons. First, because of resource limitations, organizations fund development of their information systems one application at a time.
Second, organizations may acquire some of their information systems from outside vendors. This also results in a proliferation of databases. Third, mergers and acquisitions generally result in multiple databases.
What organizational and personal factors lead an organization to have multiple, independently managed databases? Perhaps the most common reason is that end users and user groups develop their own database applications, rather than wait for the central IS organization to develop a centralized database. Also the pressures associated with rapid business change result in organizations taking a short-term, suboptimal approach rather than a careful, long-term strategy.
Data entities and Enterprise Data Model for student organization or group: This is a good in-class, interactive exercise for individuals or small groups.
Identify the similarities and differences through class discussion. A photo image of the driver: unstructured data d. The make and serial number of the scanning device that was used to scan the fingerprint: structured data f. The resolution in megapixels of the camera that was used to photograph the driver: metadata; fact describing context g. Great Lakes Insurance database suggestion: One suggested approach would be to create an enterprise database to contain all information about customers, policies, etc.
The need for an enterprise database is clear, since policy information would need to be accessed not just by the sales team but also by the actuarial department and the claims department. For inside agents, access to the database would be through an intranet, utilizing a browser-based application as the front- end.
Each outside agent would have a personal database on his or her notebook computer with only information for his or her territory. The personal database would then be synchronized periodically with the enterprise database through the use of an extranet. Record Store data model questions: a. If one is added, it is essential that the designer carefully define what the meaning of the new relationship is. It could, for example, mean that the store intends to carry all albums by a specific artist.
This duplication may lead to the problem that payments may not be properly matched to vendor orders, or that customer receipts are improperly matched to customer bills. These potential mismatches could cause issues in collection and payment of financial transactions for the organization, and may cause issues with relationships with customers and vendors. At a first glance, these duplications appear to violate the principles of the database approach outlined in this chapter.
However, the organization may have procedural or system checks-and-balances that periodically audit or synchronize the apparent data duplication throughout the organization in this three-tier scenario.
These checks-and- balances are not apparent on this Figure, but if they exist, they might compensate for the apparent violation of database approach principles. Representation of SDLC: The representation of the systems development life cycle has changed from the original waterfall metaphor. While it is a more compact representation, there are still some problems. For example, it is not purely linear. Also, it is possible to conduct steps in parallel due to time overlaps.
One additional problem of a pure SDLC model is the inability to go back from one step to another without completing the entire five-step process; most practical SDLC implementations allow movement between stages in both directions.
Consider Business Enterprise example: a. Enterprise Data Model b. Benefits from a multiple-tiered architecture for data? Processing close to the source data could reduce network traffic. Client technologies, however, can be mixed desktops, laptops, smart phones, tablets, network computers, information kiosks, etc. In addition, you can change technologies at any tier with limited impact on the system modules on other tiers.
All this will allow for data consistency and maintaining academic standards — a critical success factor for the academic unit. Contrasting database development during conceptual data modeling and logical database design phases: It is often said that conceptual data modeling is done in a top-down fashion, driven from a general understanding of the business area, not from specific information processing activities. Logical database design approaches database development from two perspectives.
First, the conceptual data model is transformed into a standard notation through normalization, based on relational database theory. This bottom-up analysis verifies exactly what data are to be maintained in the database and the nature of those data as needed for each transaction, report, and so forth. During logical database design, you combine or integrate the original conceptual data model more general information along with the individual user views more specific information into a comprehensive design.
Location of prototype database: Department databases are often developed in combination by end users, systems professionals working in business units, and central database professionals.
A combination of people is necessary since a wide variety of issues must be balanced in the design of shared databases: processing speed, ease of use, differences in data definitions, and the like. This answer assumes that the organization maintains separate development and production servers for the databases. Enterprise data models and conceptual data models: Enterprise data modeling results in a total picture or explanation of organizational data, not the design for a particular database.
A particular database provides the data for one or more information systems, whereas an enterprise data model, which may encompass many databases, describes the scope of data maintained by the organization. Therefore, the level of abstraction associated with an enterprise data model is higher; conceptual data models are be more detailed.
Iteration between physical and logical database design: Database development activities occur in each of the SDLC phases, and it is not only possible but quite frequent that feedback received during a later stage causes a project to return to a prior phase.
SDLC activities may find missing elements or errors when designing specific transactions, reports, displays, and inquiries. When a missing element is noticed, for example, it is necessary to revisit the logical database design. User views of organizational data: A good approach in developing this problem for a bank might be to carefully select the views to be developed by collecting a transaction slip, monthly statement representing each type of account , statement of earnings, etc.
Examples of data included in each message are customer information, bank information, and transaction data checks, deposits, service charges, maintenance fees, overdraft protection fees, and so forth. Statement and deposit slip views are given below, as is the combined conceptual data model.
Combining the different views could lead to the addition of new attributes or possibly entities and relationships not being shown in the original views.
Explain Figure The single line connection indicates a one-to-one relationship between the entities. In business terms: each order is billed on exactly one invoice, each invoice is written for only one order. In contrast, many payments can be made on one order. Remember to model for the exceptions. Questions about Project Data Model in Figure a.
A Customer places many orders, yet an Order is placed by one Customer. Each Order is billed on a single Invoice, and an Invoice is related to a single Order. Each Payment is related to a single Invoice, but an Invoice may be paid with one or several Payments. Each Product may be seen on multiple Order Lines.
Each Order Line tracks the specific quantity of product for the specific order. The aspect of the diagram that is difficult to describe and may also be difficult to implement and maintain is the sales goal attributes for the Product Lines and Products. Since it is expressed as Prior Year and Current Year values, this data will need to be maintained with additional programming in the database application, as there is currently no logical design to deal with this time-based data in the proposed design.
In my opinion, the reason for this ambiguity is that the prototyping approach did not yet experience the maintenance issues of date-related data in the database, due to the shortened time working with the data and sample reports.
As the end user and the analyst work through the database application over time, the need for an adjusted design will become painfully clear. SQL statements in Figure and questions: a. The field size for the ProductLineName field in the Product table may be characters. ProductID is a required attribute because it is designed as the Primary Key of the table, and in relational design Primary Key fields cannot be empty or missing.
SQL Query in Figure a. SalesToDate is calculated by multiplying the quantity by the price. Figure and new Query specification questions: a. All of the above entities will be needed for the SQL query. Summary of important properties of data models: All Entities? You can accomplish this exercise either by arranging a field trip for your class preferred , or by inviting the IS manager or other key IS person to visit your class.
Following are some of the key steps to perform: a. Select an organization. We suggest a mid-sized manufacturing company or a familiar organization in the service sector such as a hospital or bank.
Identify several mainstream applications such as human resource management, material requirements planning, and financial accounting. Determine whether these applications were predominantly developed internally, or purchased from an outside vendor or vendors.
Now determine the mix between file processing and database processing for these applications. If a database approach is used, is the data shared among the applications? To draw a figure depicting the files and databases, inquire whether the organization has system flowcharts or similar documentation that portray much of this information.
This exercise is most easily performed as a continuation of Exercise 1. Arrange to interview a database administrator or key designer as part of the same field trip.
Discuss whether the organization maintains user-oriented metadata, or only technical metadata. Where is this metadata maintained: within individual applications, in one or more CASE tool repositories, or elsewhere? If the student has selected an established company with a fairly extensive information systems department, they will find that the company is either already very involved in Web-enabling some or many parts of their business, or that they are actively planning to expand the scope of their involvement.
You may want to encourage your students to use this question to explore where the company sees itself going with regard to the Internet. Many older companies are struggling very hard to adjust and remain competitive as the Internet dramatically affects business models.
Again, as in the previous field exercise, this exercise will help students to integrate their new textbook knowledge with the realities that organizations must face. Students will probably find prototyping being used for smaller database applications.
Large systems that require a new database are more likely to use the SDLC, requiring a team of information systems professionals, including database designers and programmers. The systems development process for Web applications can be similar, with prototyping being employed. However, students may find that there is a lot more testing involved with Web applications, since one has less control over the client interface.
Students are likely to find some of the following roles on the information systems development teams in larger organizations: a. Systems analysts, who analyze the business situation and identify the need for information and information services to meet the problems or opportunities of the business b. Database analysts, who concentrate on determining the requirements and design for the database component of the information system c.
Users, who provide assessment of their information needs and monitor appropriateness of the developed system d. Programmers, who design and write computer programs that have embedded in them commands to maintain and access data in the database e. Other technical experts, with facility in networking, operating systems, testing, and documentation g. A senior systems or database analyst, who will be assigned to be project leader, who is responsible for creating detailed project plans as well as staffing and supervising the project team; this good project leader will possess leadership, management, customer relations and communications, technical problem solving, conflict management, team building, and risk and change management skills.
In smaller organizations, students may find that these roles are combined and performed by fewer people because the smaller organizations do not have the additional staff to assign to a diverse team. Thus, fewer people will cover these same functional responsibilities by each person having multiple roles to fulfill.
Many employees in small organizations develop deep skill sets in programming, data administration, or technical database administration expertise. If a CASE tool is being used, a repository stores descriptions of the data entities and the business rules, detailed descriptions of CSFs, and objectives. The information systems department analyzes all of them. Throughout the systems development process, CASE tools are used to develop data models and to maintain in the repository the metadata for the database and applications.
A repository maintains all of the documentation too. Various people might use the CASE tools and associated repository during a database development project: systems analysts, database analysts, users, programmers, database and data administrators, and other technical specialists.
As a significant new portion of a project is completed and entries are made in the repository, a review point occurs so that those working on the project and funding the human and capital resources of the project can assess progress and renew commitment based on incremental achievements. Student answers will vary depending upon the organization and the functional area chosen for the interview.
As long as students are encouraged to contact individuals in larger or corporate environments, answers should reflect a variety of approaches to retrieving data, kinds of systems accessed for data retrieval, frequencies of data retrieval, levels of satisfaction with data access and retrieval, and challenges experienced. This would be a good exercise to assign for out-of-class investigation, and then use in-class time for students to meet in small groups to share their results with one another.
A subsequent large-group discussion led by the instructor can readily illustrate the different experiences and raise student awareness of the diversity in organizational approaches to data storage, access, and retrieval. Student answers will vary. Project Questions Initial Analysis Memo a. Approach to addressing the problem There is obviously no one right solution to this question, and it does not make sense to provide a solution that would suggest that there is.
Any solution they will adopt needs to take this into account: heavy infrastructure or support requirements would, in all likelihood, make a specific approach impossible immediately. There are a number of elements of the system that can be implemented independently and as long as the data management architecture is at least tentatively designed in advance, the independent components can be integrated over time.
Thus, suggesting a development model that is based on a set of time-boxed iterations is reasonable. Would it make any sense for FAME to own its own hardware and system software infrastructure?
Accomplishments, organizational goals, and functionality o The new system would o Reduce errors in contracts, scheduling, and billing o Make information regarding artist availability centralized and more readily available for everybody, thus allowing faster decisions o Make it possible to speed up the business processes, at least theoretially allowing FAME to get the artists paid faster o Make it easier for the artist managers to review recommendations and other information regarding prospective artists.
Our recommendation is that you frame the project in the context of your semester, using real time constraints. Possible questions for Mr. Forondo o How would he define the priorities between the various functionalities and potential benefits of the system?
Forondo has a reasonable idea of the cost of developing such a system from scratch and if he is willing to pay. Forondo is specifically worried about? Enterprise Data Model Please see the following page for the response to this question. Related Papers. By Andrew Tugume. Testing the Data Warehouse. By wayne yaddow.
The role of business models in enterprise modelling. By Paul Johannesson. Data Warehousing Methodologies. By Vijay Gupta. By Ibrahim Wada. Download file. D who can delete the data. Answer: D LO: 2.
B terms. C facts. D nuggets. Difficulty: Easy Classification: Concept AACSB: Information Technology 1 4 Data modeling may be the most important part of the systems development process because: A data characteristics are important in the design of programs and other systems components. B the data in a system are generally less complex than processes and play a central role in development.
C data are less stable than processes. D it is the easiest. Answer: A LO: 2. B weak entities. C associative entities. D smush entities. B creating data.
C updating data. D removing data. B attributes. C cardinals. D relationships. B a strong entity and its associated weak entity. C a co-dependent relationship. D a double-walled relationship. B specific to the organization. C as short as possible. D a singular noun. Answer: C LO: 2. B coexisting entity. C relationship. D cross-function. B required attribute. C optional attribute. D multivalued attribute. B entities. C relationships. D descriptors. B composite attribute. C required attribute.
D fuzzy attribute. B one. C two. D three. B identifying characteristic. C degree. D counter. A It depicts a ternary relationship.
B It depicts a many-to-many relationship. C Item represents a column. B a relational attribute. C a derived attribute. D a multivalued attribute. A Choose an identifier that is not stable. B Choose a null identifier. C Choose an identifier that doesn't have large composite attributes. D Choose the most complex identifier possible. B composite identifier.
C identifying attribute. D relationship identifier. Difficulty: Easy Classification: Concept AACSB: Information Technology 13 35 An entity that associates the instances of one or more entity types and contains attributes specific to the relationships is called a n : A associative entity. B build entity. C gateway entity. D smush entity. B an entity instance can participate in only one of several alternative relationships. C an entity instance cannot participate in a relationship with another entity instance.
D an entity instance bridges other XML documents. A A person can marry at most one person. B A person has to be married. C A person can marry more than one person, but that person can only be married to one person.
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