Selection and Induction Essay Example for Free

Selection and Induction Essay Inadequate recruitment can lead to labour shortages, or problems in management decision making. Recruitment is however not just a simple selection process but also requires management decision making and extensive planning to employ the most suitable manpower. Competition among business organisations for recruiting the best potential has increased focus on innovation, and management decision making and the selectors aim to recruit only the best candidates who would suit the corporate culture, ethics and climate specific to the organisation. The process of recruitment does not however end with application and selection of the right people but involves maintaining and retaining the employees chosen. (State Government of Victoria State Services Authority, 2008) The housekeeping department is the most important department in hospitality world. Housekeeping is responsible for cleaning the hotel’s guestrooms and public areas. This department has the largest amount staff, and its operations are the most influential from both external and internal factors. Thus they have an ever chancing requirement for staff. RECRUITMENT French and Rees (2010) Defines recruitment as, â€Å"a process to discover the sources of man power to meet the requirements of the staffing schedule and to employ effective measures for attracting that manpower in adequate numbers to facilitate effective selection of an efficient workforce. † Edwin B. Flippo defined recruitment as â€Å"the process of searching for prospective employees and stimulating them to apply for jobs in the organization. † In simple words recruitment can be defined as a ‘linking function’-joining together those with jobs to fill and those seeking jobs. The general purpose of recruitment is to provide a pool of potentially qualified job candidates. For a more detailed specification: (see Attachment 1) The process 1. A need is created through any number of factors within an establishment. From the change in seasonal occupancy, personal factors of staff or managerial requirements. As in the case of the ABS Hotel, a member of the housekeeping department has been granted a transfer due to personal issues. Now a position has been created that needs to be filled. The HOD of the department will now access the vacancy and if need be, he will file a request for the recruitment of a new staff member. (See Attachment 2) 2. The request will be filled and accessed by the Hotel’s Human resources Manager, and he will then have a meeting with the HOD from the Housekeeping department to discuss the need for a new staff member. If the HR manager finds the request valid he will then go about discussing the positions measurable standard with the HOD. This will result in the Job analysis of the required room attendant by which applicants will be measured. See Attachment 3) 3. The HR manager must then apply to the Hotels Chief Financial Officer if there are funds available for both the recruitment process and the annual salary of the new staff member. As is the case with the current position at the ABC Hotel, the annual salary can be paid as it would have been paid to the previous room attendant. 4. Once the CFO has validated the financial aspect of t he request, the HR manager and the HOD of the housekeeping department must apply to the General Manager for his approval of the recruitment. . If the GM denies their request, the process will stop. If the GM accepts the request the HOD’s part of recruitment has been completed, and the HR manager starts the formal process of recruitment. 6. The HR manager does research into the Labour market, Economy and the Expansion of the company. The Labour market’s geographical and demographical information will assist the HR manager in calculating the environment were the best suitable candidates can be found and through use of which measure can they best be reached. The studying of the economical present and future will assist the manager in accessing if it would be affordable to hire the new employee and what the market rate for the positions salary is. The growth of the company has the biggest impact on the recruitment process, for if the company has to decline or plans to â€Å"float† through the following year then the appointment of a new staff member will result in a profit expenditure, which renders the recruitment process a loss. As is the current state of the ABC Hotel the three factors are all positive and thus the HR manager will continue with the recruitment process. . The HR manager must utilise the company resources to decide whether to advertise the vacancy internally, externally and by which technique to best reach the required labour market. [ For an explanation of internal-, and external advertising, (see Attachment 1) ] 8. The HR manager must now utilise the information gathered from the previous two steps to thoroughly plan the advertisement. All relevant information regarding the position needs to be within the method of advertising and must create a positive image for the organisation. (see Attachment 4) 9. If the HR Manager has done his job correctly, persons will apply for the position. SELECTION The size of the labour market, the image of the company, the place of posting, the nature of job, the compensation package and a host of other factors influence the manner of aspirants are likely to respond to the recruiting efforts of the company. Through the process of recruitment the company tries to locate prospective employees and encourages them to apply for vacancies at various levels. Recruiting, thus, provides a pool of applicants for selection. Selection is defined by French (2012, p. 76) as the process of picking individuals who have relevant qualifications to fill jobs in an organisation. The basic purpose is to choose the individual who can most successfully perform the job from the pool of qualified candidates. The purpose of selection is to pick up the most suitable candidate who would meet the requirements of the job in an organisation best, to find out which job applicant wil l be successful, if hired. To meet this goal, the company obtains and assesses information about the applicants in terms of age, qualifications, skills, experience, etc. the needs of the job are matched with the profile of candidates. The most suitable person is then picked up after eliminating the unsuitable applicants through successive stages of selection process. How well an employee is matched to a job is very important because it is directly affects the amount and quality of employee’s work. Any mismatch in this regard can cost an organisation a great deal of money, time and trouble, especially, in terms of training and operating costs. In course of time, the employee may find the job distasteful and leave in frustration. He may even circulate negative information about the company, causing incalculable harm to the company in the long run. Effective election, therefore, demands constant monitoring of the ‘fit’ between people the job. (French and Rees, 2012, p. 176) The Process 1. The Curriculum Vitae’ of applicants are received. 2. The applications will now be scrutinised according to the measurable standard. 3. A database is created wherein all the information of applicants are entered and stored. This database is a very essential and useful tool. It has all the information applicants included on their CV’s, this information can be used as a record of how applicants were chosen or declined. It holds the record to prove that the selection process was neither biased nor discriminative and has complied with both the Labour Relations and the Employment Equity Acts. It is also a useful reference base which can be used for future manpower forecasting or a base of possible employees for future positions. Thus saving on recruitment costs. 4. The applications are now sorted by the HR manager into three â€Å"piles†. Successful-, For Review- and Unsuccessful applicants. 5. The unsuccessful applicants must be sent a letter of their unsuccessful attempt. The letter will contain the reason the establishment declined their application and will wish them well for future applications. 6. From the Successful applicants a short list will now be drawn up, by both the HR Manager and the Housekeeping HOD, to show the best possible candidates for the position. This can sometimes be a difficult and time consuming process. To ease the process follow these guidelines. (see Attachment 5) 7. Once the best possible candidates have been chosen from the shortlist, they will be telephonically contacted and informed that they are a possible candidate for the position. During the phone call a short pre-interview will be conducted to confirm the critical information with the candidate and to inform them of their formal interview. 8. Application forms are sent via email or post to the candidates for them to formally apply for the position. These need to be sent back to the establishment as they will be used to gather information on candidates to better structure the interviews. 9. Using the candidates I. D. numbers a background check will be done on applicants for criminal record or blacklisting. According to JHON BOTHA, director of the Production Management Institute, this has become a necessary step due to the Labour laws in South Africa. Business Day October 11th, 2012. see Attachment 6 ] 10. The HR manager and HOD of the Housekeeping department must setup the formal interview structure and question the candidates. 11. After the interview the candidates will write a short aptitude test to see if their norms, values and attitudes align with the est ablishments. 12. The HR manager and The HOD will now decide on the best candidate for the position. If none of the candidates are suitable for the position, they may refer back to the candidates which didn’t make the short list or the applicants for review and repeat steps 8-11. If no candidate or applicant meets the requirements, then the recruitment and selection process must be reviewed and restarted. 13. If a candidate has been chosen for the position, they will be informed of their success telephonically and given further instructions regarding their first day of employment and induction. If the chosen candidate declines the offer then the HR manager must choose another and repeat step 12 and 13. 4. The unsuccessful candidates will receive a phone call informing them of their unsuccessful attempt but will assure them that they will be considered for future positions. INDUCTION Induction can be defined as the first step towards gaining an employees commitment, it is aimed at introducing the job and organization to the recruit and him or her to the organization. It involv es orientation and training of the employee in the organizational culture, and showing how he or she is interconnected to (and interdependent on) everyone else in the organization. See also orientation. (Target Selection 1986) The Induction process has several important objectives (Grobler et al. 2002) : †¢Acquainting new employees with job procedures. †¢Establishing relationships with co-workers. †¢Creating a sense of belonging among employees. †¢Acquainting new employees with the goals of the organisation. †¢Indicating to the employees the preferred means by which these goals should be achieved. †¢Identifying the basic responsibilities of the job. †¢Indicating the required behaviour patterns for effective job performance. (Grobler et al. 2002) The Process Day 1: Introduction to the establishment and work area Person Responsible: HR Manager †¢Mission, Vision, Objectives of work area †¢How the work area fits in to the wider establishment †¢All key operational and social areas to be visited. Introduction to other members of staff Person Responsible: HR Manager †¢Go through organisation chart †¢Discuss roles and responsibilities of staff in general terms. †¢May also want to extend time to allow visits to key contacts out with work area. Introduction to the other teams within the Work area Person Responsible – Line Manager †¢Purpose/Activities of the other teams/work areas †¢How the team fits in to the work area †¢How the work area fits into the University Day 2: Terms and Conditions Person Responsible – Line Manager †¢Ensure new start has viewed and understood information contained in the Information for New Employees this contains important information on terms and conditions. Performance Standards Person Responsible – Line Manager †¢Outline specifics of job role – (job description) †¢Define goals, objectives, and expectations †¢Review probation and performance and development review/ ADR/ appraisal process. Culture of the Work area Person Responsible – Line Manager/Nominee †¢Make new start aware of local arrangements regarding hours of work, holiday requests, sickness procedure, after hours working, dress code, lunch arrangements, etc. †¢Other University procedures e. g. internet and e-mail usage, transportation and parking, etc. Office Systems Person Responsible – Line Manager/Nominee †¢Review processes for using office equipment such as: computer, telephone, voicemail, fax, printer, photocopier, etc. †¢Review processes for using other university equipment/systems such as: libraries, laboratories, open access computers, etc. Review computer security, and software usage. †¢Consider environmental efficiencies (waste, recycling, energy) Health and Safety Person Responsible – Health ; Safety Co-ordinator/ Line Manager †¢Physical – fire exits, fire alarms, fire evacuation procedure, fire-training arrangements, manual handling, fir st-aid arrangements, VDU usage, and other arrangements as required. Day 3 and 4 Job Specific Training and Development -Person Responsible – Line Manager/Nominee †¢Role specific development needs should be reviewed and a suitable programme of training should be planned that aligns the individual’s skills to their core duties. Staff with line management responsibilities should be clear as to their duties and attend any relevant training. †¢Outline the use of annual performance and development reviews/ ADR as one method for determining on-going role specific development needs. †¢Introduce University wide training and development opportunities available to staff. †¢Review use of personal development planning tools (i. e. PDP) Week 1 4: The new employee should be partnered with a buddy / mentor and work with and alongside them to learn the operations, in’s-and-out’s and daily routines of the position. Week 5 – 6: The new employee should now be able to function independently, but will still require supervision. Week 7: Monitoring and Evaluation Person Responsible – Line Manager †¢It is important that the Induction programme is monitored and reviewed. †¢Throughout the period regular review meetings should be held and any adjustments made. †¢The new employee should be informally interviewed to access his progress and experience of the working environment. Week 8 12: Probation -Person Responsible – Line Manager For new staff the Probation Policy will apply, at the end of three months the new employee will now be a permanent employee. This will have ensured continued efficiency and productivity. CONCLUSION At the end of what could be a short or long process the ABC Hotel will now have the new room attendant which would have fit in perfectly into the organisation to ensure continued productivity and efficiency. If each of the steps of all three processes of Recruitment, Selection and Induction have been followed and done according to the Hotel’s policies and procedures and the standards set by management then the present and future manpower planning will be a success. An awareness of issues and concepts within this area is an important tool for all those involved with leading, managing and developing people – even if they are not human resource managers per se. A recognition of the importance of this aspect of people management is not new, and ‘success’ in this field has often been linked with the avoidance of critical failure factors including undesirable levels of staff turnover and claims of discrimination from unsuccessful job applicants. It has been argued here that it is also possible to identify aspects of recruitment and selection which link with critical success factors in the 21st century context, differentiating organisational performance and going some way to delivering employees who can act as ‘thinking performers’. It is proposed, for example, that a competencies approach focusing on abilities needed to perform a job well may be preferable to the use of a more traditional matching of job and person. (French 2010)

Is Important To Study The Media Consumption?

Is Important To Study The Media Consumption? What is the media, why is it important to study the media and does it have an impact and can it change the way we think and behave? These are questions that are important in the study of the media industry. The media is a communication tool that is used to transfer messages to the general public. There are many types of media, for example the radio, television, newspapers and etc. Its important to be media literate as the media can be used to change and leave a lasting impact on an individual. The media is one of the most powerful tools that have been created. The media plays a vital role in an individuals perspective on political, economic and socio-cultural issues. According to Bazalgette Media studies open up your understanding of how things work, how people become informed or misinformed and how the myths and ideologies that govern all our lives are created and sustained. (Bazalgette, 2000). The media continually changes and evolves, the term media studies means different courses priorities different media; different theories and different learning outcomes (Bazalgette, 2000). Since this subject is still new there are a lot of disagreements on how media should be interpreted and it is also a hybrid subject as the idea that it came about comes from a variety of sources (Bazalgette, 2000). Media studies is also considered an academic discipline as it binds the different types of hybrid disciplines such as semiotics, structuralism, sociolinguistics and a lot more and th ere are no limits to an individual as how to analyze the media. The analysis of media is very important for this particular subject. Media studies are normally associated with the English language subject and also English Literature. However the difference is rather apparent and media studies courses uses economics, politics, psychology and sociology perspectives as ways to understand the media as well as requirements to consider texts from different contrasting perspectives. The English subject on the other hand, deals with reading and writing skills as well critical analysis. Bazalgette goes on to state that media studies are essentially political, it is political to ask questions like who owns a certain media and why (Bazalgette, 2000). This is known as media ownership, the individual consuming the media needs to have knowledge about who owns what media. Is it owned by an individual, a small firm or a large conglomeration? The understanding of what is studied and why it is studied is a very important topic in media studies. According to Bazalgetee there are five reasonings, the first is popularity. Why is there a certain game show, movie, song, or computer game studied more that another is simply because a lot if people like them (Bazalgetee,2000). This shows how audiences are manipulated and what the preferred media is. Second is exemplification, which means worthiness of study. It is characteristic of media studies that it tests and reviews its own theories, asking students to consider a range of examples and then to figure out not only the usefulness of a theory but also its limitations (Bazalgette, 2000). The third is notoriety, which helps us analyze media text in the contexts of social, political and culture. Most of these are controversial documentaries, movies or songs etc. The fourth is turning point, where selected text as stated in the previous point, can be significant without being notorio us. The final reason is aesthetic value, is a way of picking out important meanings from a text and making judgements. Important influences in media studies are self and experience in a mediated world. The self is seen as a product of the symbolic systems which precede it (Thompson, 1995). Identity and capacity to make sense of the world around us is said to be an outcome of a symbolic project. Controversies to how the media construct our personal lives and the role it plays as well as the views of the world about it (Thompson, 1995). Studying the media is also a very good way to understand the different jobs in the media industries and how these works are changing. The film and broadcasting industries have been predicted to face a shortage of skills it the time to come and therefore will be in need of people who are literate about the media Media study is a course that is rather challenging and it will somehow make a difference in our lives. It gives us the power of choice as well as questioning (Bazalgette, 2000). The media is like history as it interprets the past to show us what has gone into making us what we are now It also helps us to understand the workings of our world and it helps us use our critical thinking skills as well as helping us definite how we communicate with others help us determine the cultural fabric of our lives and it helps us interpret our world and its values and ideas brings us political and ideological messages continuously and like technology, the media always adopt the leading edge of modern technological innovation. As we have understood why its important to study the media, we also need to look at how the media is studied. There are two different schools of thought, one being American and the other European. Sinclair states that European and American theories are identified as application to media and communications. They are differences between these two and the European is characterized as interpretive and holistic in scope and American as empirical and micro (Sinclair, 2002). What this means is that we can study the media according to either the American way or the European way, but the outcome of the study would be different. The European way relays heavily interpretive and holistic in scope that is taking a macro-perspective, looking down on society on a whole (Sinclair, 2002). It exists most often in the sociopolitical stance of Marxists. This school of thought originated from the Frankfurt School, a group of Marxist based at Frankfurt in Germany, who had developed their critical theory. This theory is now usually called cultural Marxism or Western Marxism (Sinclair, 2002). Western Marxism is said to incorporate semiology and structuralism in the media and Ideological Critique argues that the media induce misunderstanding (Sinclair, 2002). The British were seeking to reconcile traditional British Marxism, which had little conception of culture at all with a theoretical critique of the media (Sinclair, 2002). In 1960 the University of Birmingham established a Center for Contemporary Cultural Studies and taught a combination of literary criticism and Marxist sociology. The Birmingham School emphasized the significance of media images and representations within the context of social and political conflicts. Political Economy studies the production and distribution of media content, It does not argue that media content under capitalism is ideological but somehow had assume that audiences fall under the ideological influence. The American way is of direct observation and controlled measurable occurrences. The American Empiricism defines content analysis as a systematic and quantifiable method to describe and analyze the meaning of the media messages (Sinclair, 2002). Harold Lesswell (1948) said that a convenient way to describe communication is to answer these questions, who, says what, through which channel, to whom, with what effect? Through this model we can study the way messages are transferred and to whom. Textual analysis is a way of gathering and analyzing information in academic research, it is also a way to approach media texts to try to understand their meanings (McKee, 2001). Content analysis breaks down the components of a program or newspaper into units which you are able to count them and replicates can be done. Semiotic analysis on the other hand, breaks down different elements of a text and labels them. In media studies, there is never a claim to whether a text is an accurate or inaccurate representation of reality. This means there is never a single correct way of any text (McKee, 2001). The text is likely to be interpreted through genre, the different codes producers and audiences communicated with and context, which is divide into 3 levels, the rest of the text, the genre of the text, the winder public context in which a text is circulated (McKee, 2001). Since there is no correct way of interpreting a text we need to learn how to understand media text and the world of rea lity. One way is by understanding the elements of language and culture, the form and context that shape the meanings that are available to us.

Consider the implications of the title, Persuasion Essay -- English Li

Consider the implications of the title, Persuasion â€Å"Something intended to induce belief or action† is how the Oxford Dictionary defines the term persuasion. To consider the implications of the title successfully, it is essential that we first understand the term persuasion within the context of the novel. The Oxford Dictionary also defines the term ‘persuade’ as â€Å"to successfully urge a person to do; to talk into or out of an action†, â€Å"to attract, lure or entice† or as â€Å"to talk earnestly with a person to secure agreement or compliance.† By these definitions we can notice that the concept of persuasion is ever-present throughout Austen’s novel. One of Austen’s traits is that her titles appear to offer some indication towards subject content; ‘Sense and Sensibility’,’ Pride and Prejudice’ and in this novel; ‘Persuasion.’ The first of these titles seems to suggest a tone of appraisal and the second, a tone of condemnation. From this recognition, we can also notice that Austen’s novels deal with the concept of moral perameters. ‘Persuasion’ however, does not seem to provide a clear indication of the nature of the subject matter. Yet isn’t persuasion less of a moral concept than ‘Sense and Sensibility’ and ‘Pride and Prejudice’? It seems therefore, that ‘Persuasion’ can be seen to challenge the idea of social class and position as opposed to the large issues of morality which are seen in ‘Sense and Sensibility’ and ‘Pride and Prejudice’. We must not consider the implications of the title with a closed mind. When Jane Austen penned her last complete novel, ‘Persuasion’ could be interpreted in two different ways; a strong belief in the process of persuasion of one’s thinking and secondly, the act of being pers... ... Lady Russell’s moral inferiority as Anne â€Å"lost her bloom† due to the persuasion of Lady Russell. Idealised love is, in fact, performed away from the public in ‘Persuasion’ as we see that public interferences are able to turn relationships sour; â€Å"a short period of exquisite felicity followed, and but a short one. Troubles soon arose, Sir Walter on being applied to†¦Ã¢â‚¬  From Anne and Wentworth’s lasting affection, we can see that most persuasion in the novel revolves around the concept of love. At the time of writing ‘Persuasion’, there had been a change in popular taste from Augustan values to Romanticism with its focus upon intense feelings. By carefully weaving between Romantic and Augustan values, Austen leaves it up to the reader to consider the case of romance between Anne and Wentworth, determining whether we find ourselves for or against persuasion.

Compare and contrast two poems that contain different representations :: English Literature:

Compare and contrast two poems that contain different representations of school pupils. 'Comprehensive' is a representation of a comprehensive school, in the way that the diverse mixture of cultures are included in the poem. Each pupil has a different life and culture, and the pitfalls of comprehensive schools are clearly shown by the way in which each pupil is represented. The first pupil is African, and homesick, and is not happy in England. It seems as though she misses her culture, and feels as though she is being stifled by the British culture. This is also true of 'In Which The Ancient History I learn Is Not My Own.' The boy represented in this poem is homesick, and also feels stifled by the British culture, due to the fact that he is being almost forced into it, thus not allowing him to enjoy his own Irish culture. The teacher wants him to learn 'The English Kings, the famous battles and God's grace in History' which causes him to begin to forget his own History, which he is desperately trying to hold on to. The second pupil in 'Comprehensive' is a boy named 'Wayne,' who is depicted as a stereotypical boy. He is precocious in the way he thinks he is 'too old for games' and believes he is old enough to support something so controversial, when clearly he does not understand it to a full extent. He holds a very patriarchal view, especially when it comes to women. He believes that they are there to have their knickers pulled down, as it were and cook for him. Such a strong attitude as this for a pupil of only fourteen years of age inevitably will cause friction between him and his peers and teachers. And in a school of mixed culture, this would not bode well. Although the teacher has not such a derogatory attitude as Wayne, she is similar in the way that she has very strong views that she places upon the young Irish boy in, 'In Which The Ancient History Is Not My Own.' The Teacher is very patriotic, and expects the pupil of a completely different culture to be the same about England. An example of this is when the teacher describes the Roman Empire as 'the greatest Empire ever known- until our time of course.' This is the kind of attitude that is almost stripping the boy of his patriotism of his own land, and restricting him from learn about his own History. He has had to take on another cultures history and been forced to take it on as his own. Similarities can be made between the young Irish boy and 'Ejaz' and

Case Analysis_The University Art Museum Essay

Executive Summary This report was commissioned as a case analysis to examine why the last two directors of the University Art Museum were seemingly at odds with the university and failed in their mission to lead the museum into the future. Further it provides prospective on how to move the museum into the future through successful management. Case Analysis The University Art Museum was a generous gift donated by the son of the university’s first president, who was also a campus alumnus. The university took great pride in the museum and even highlighted the museum’s photo on campus brochures and catalogs for years. However, in recent years university was not exactly pleased with the direction the museum was headed under either of its most recent two directors. It became abundantly clear that the directors had a different vision for the museum than did the university faculty. There was so much tension amongst parties that the previous director had â€Å"sharply attacked the faculty as â€Å"elitist† and snobbish† and as believing that â€Å"art belongs to the rich,† (Daft, 2013). What we gather from the case for analysis is that university did not clearly outline the direction of the museum, provide a mission statement, or make any formal written policy about how to run the museum or move the museum into the future. We also gather that prior to 1998 the museum ran just fine without the university needing any formalities. This could partially equate to the fact that the original director and his successor were previous students of the university. As students of the university they may have already had a pretty good idea of how the university operated. Additionally, the original director was also the founder of the museum. Whatever the case may be it wasn’t until the university began hiring outside the university that there seemed to be a major disconnect. At this point it is clear that there are some design essentials that need to be incorporated before hiring another director. With that being said, organizations exist for a purpose and that purpose needs to be clearly defined. The university faculty should first decide the organization’s strategic intent which includes a clear and  specific mission, a vision, and the principles of the university. Additional aspects of strategic intent are competitive advantage and core competence. In knowing the competitive advantage of the museum and the core competence, the faculty will be better positioned to build a strategy. Once the mission and goals are established the university should be able to set clear operating goals. Additionally, the faculty members need to take a long look at what they consider the failures of the previous two directors and see how their attempts to move the university into the future can be adjusted to fit the needs of the university, the needs of the community and lastly, paint the university in a better light, one not viewed as â€Å"elitist† or â€Å"snobbish†. Simply returning the university to its previous state could prove to be detrimental. Lastly, the university needs to have some formal measure in place to assess effectiveness of the strategies set forth. Simply put, just because the faculty is happy with the direction the museum is headed, doesn’t make it a successful venture. Conclusion  In conclusion, it is clear why the previous two directors have failed to be successful in fulfilling the mission of the university. Quite simply, there was no mission defined, no goals, no formal policies or principles, and no vision. If any director is to be successful the university needs to take the appropriate measures in spearheading that success. First and foremost, a mission statement must be formulated. The organization needs to understand the competitive advantage and core competence of the museum and built a suitable strategy or strategies around these values. Lastly, there needs to be a formal measure in place to assess the effectiveness. Once the university has taken the necessary steps to lead the museum in the direction it wants for the future, they will be far more successful in finding the right director for the job. Most importantly, the director will do a much better job of meeting the goals of the university faculty. References Daft. R. L. (2013). Organization Theory & Design. Mason, OH: South-Western, Cengage Learning.

Vacant Chapter 6 Surprises

After four months, I continue to be astonished by what Emily can do with a dented, often label-less, can. She says it's all the Julia Child reruns on PBS, but I don't care who's to credit. Dinner is on the table every night with mismatched plates and silverware, and our economy paper towels are always folded into decorative shapes. It hasn't escaped my notice at how much I enjoy seeing our laundry mingled together, either. The bottom line for me is that she makes even this place seem like home. After Emily agreed to move in with me – which was no small feat – it took a month until she stopped knocking, then cracking the door and yelling, â€Å"Ethan?† before she would enter through the front door. It was as if she thought I would get mad if she didn't practice her self- imposed ritual. While her discomfort with calling this her home still lingers, it's just the tip of the iceberg concerning our†¦ issues. Initially, she'd been particularly insistent about getting a job and wanting to help financially. I hadn't argued, thinking she was nearly done, if not completely finished, with school. I hadn't bother to ask what her status was, figuring she was old enough to make that decision herself. So, it was with eagerness that I helped her look for a job. One roadblock was her lack of identification. Employers want an ID, but of course, Emily didn't have any. We spent an entire day at City Hall getting the required documentation and social security card, so we could then go to the DMV. That was the day I found out she was barely old enough for a driver's permit – let alone a driver's license. Emily insisted she was nearly eighteen when we met, but I found out she wasn't even close. Shock didn't even begin to explain what I felt at the revelation of her real age. She hadn't lied about when her birthday was; it was a month after she moved in, as she'd first said. However, she was turning sixteen, not eighteen. While I was monumentally upset by her deception, I got it. She was living with the fear of being herded into a state system that could feel like you were being fed to the wolves. I couldn't really blame her. After I got over my initial anger about her lie and the additional guilt of some of the inappropriate things I may have fantasized about her, I realized Emily missed the milestone of sweet sixteen. I remembered a co-worker talking about her sister's sixteenth birthday and the excitement that went along with the momentous occasion. Emily insisted she didn't want anything special and maintained that by finding me, she'd already received more than she ever hoped for after her mother's passing. The celebratory sad-assed cookie I had on my twenty-first birthday came to mind. I instantly knew it wasn't good enough for Emily, so I went into work and ordered the most extravagant and girly cake our bakery had – regardless of the fact it was almost forty bucks, my usual weekly food budget. Her reaction to the cake was like a kick to the stomach. When I brought it home, Emily cried, explaining that even her mother had never gotten her a cake since cake wasn't something you buy on a stric t budget. That was the moment I decided Emily would never go without again. Knowing that cake was so special made it all the more enjoyable when I ate it every meal the week that followed. â€Å"Ethan, go wash your hands please. Dinner is ready.† It never fails. The girl can literally watch me walk from the bathroom, knowing I've just scrubbed up, but she will still tell me to wash again, and I will. I know that she's tied to the routine, not really the cleanliness factor. Many who have been in a homeless situation will cling to routines for the comfort and solace they bring. We sit and eat in silence for the first few minutes of the meal. It's always balanced, particularly since she's taking a health class this semester and preaches the benefits of healthy eating habits and exercise. Sometimes it makes me laugh because she sounds just like one of those infomercials she occasionally watches in the middle of the night after she's had a bad dream. There are times I think it's more than just nightmares, though, when she wakes at night. She carries a lot of guilt around with her given our situation. Emily feels like she should contribute to the household with money. I feel like she needs to be in school, getting an education. Even though legally she could drop out, I'm constantly reiterating that school is her job, and there will be plenty of time for her to contribute in the future when she's a full-fledged taxpayer. â€Å"Hey, Ethan?† Emily asks cautiously, while pushing her cube steak around on the plate. I'm a bit nervous since she says it with hesitance. She hardly asks for anything, and when she does, she makes it seem like she's about to ask for a million dollars, but it's usually something small and relatively insignificant. This time, though, the accompanying look on her face indicates this isn't simple. I put my fork down and look up, giving her my full attention. â€Å"So, Christmas is coming.† I inwardly groan, not because she's brought it up, but because I participate in as little of the Holiday Cheer as possible. It's been awhile since I've celebrated the birth of Christ, mainly because I don't believe in God. Realistically, I see the holiday as an opportunity to earn extra money as I work all the shifts so everyone else can spend time with their families. I try to dislodge my anxiety about the topic but it doesn't work. The holidays are about commercialism and consumerism. Plus, I can't afford to buy gifts. â€Å"Yeah, I usually work Christmas. I get double time.† My dinner still sits heavy in the pit of my stomach. I know I should give her a special day. â€Å"Oh.† Now I feel like a jerk who's robbed her of the magic of Christmas. â€Å"Like all day or just part?† â€Å"The store is open from seven until two, then closing early.† I know why she's asking, but it doesn't keep me from playing stupid. â€Å"Why? What's up?† Emily finally stops pushing her battered piece of meat around on the plate and looks up. â€Å"I was thinking†¦and you don't have to†¦it's just something that†¦I mean, you can, but if it makes you uncomfortable†¦Ã¢â‚¬  I finally stop her rambling by touching her hand. My hope is that she will refocus her thoughts with my unexpected gesture. I'm successful. Emily sits up a little straighter, squares her shoulders, and wipes her mouth with her paper towel-slash-napkin. â€Å"I want to spend Christmas at the shelter. You know†¦it's the last place I was with my mom.†

Database: Entity-relationship Model

Appendix A: A Practical Guide to Entity-Relationship Modeling A Practical Guide to Entity-Relationship Modeling Il-Yeol Song and Kristin Froehlich College of Information Science and Technology Drexel University Philadelphia, PA 19104 Abstract The Entity-Relationship (ER) model and its accompanying ER diagrams are widely used for database design and Systems Analysis. Many books and articles just provide a definition of each modeling component and give examples of pre-built ER diagrams.Beginners in data modeling have a great deal of difficulty learning how to approach a given problem, what questions to ask in order to build a model, what rules to use while constructing an ER diagram, and why one diagram is better than another. In this paper, therefore, we present step-by-step guidelines, a set of decision rules proven to be useful in building ER diagrams, and a case study problem with a preferred answer as well as a set of incorrect diagrams for the problem.Database Management System a nd DataThe guidelines and decision rules have been successfully used in our beginning Database Management Systems course for the last eight years. The case study will provide readers with a detailed approach to the modeling process and a deeper understanding of data modeling. Introduction Entity relationship diagrams (ERD) are widely used in database design and systems analysis to represent systems or problem domains. The ERD was introduced by Chen (1976) in early 1976. Teorey, Yang, and Fry (1986) present an extended ER model for relational database design.The ERD models a given problem in terms of its essential elements and the interactions between those elements in a problem domain. The ERD can serve as the basis for databases, which store data about the problem domain, and which use, manipulate, and constrain that data. Experts in systems analysis and database design are adept at identifying user requirements and then translating them into corresponding components of the model. Many books and articles just provide a definition of each modeling component and give examples of pre-built ER diagrams. Beginners in data modeling have a great eal of difficulty learning how to approach a given problem, what questions to ask in order to build a model, what rules to use while constructing an ER diagram, and why one diagram is better than another. 213 Appendix A: A Practical Guide to Entity-Relationship Modeling Ahrens and Song (1991) present a set of requirements elicitation template sentences, structured English template sentences, and some decision rules for database modeling. This paper presents a set of heuristic rules which improve upon those presented by Ahrens and Song (1991), together with a detailed case study analysis.We include step-by-step guidelines, a set of decision rules proven to be useful in building ER diagrams, and a case study problem with a preferred answer as well as a set of incorrect diagrams for the problem. These guidelines and decision ru les have been successfully used in our beginning Database Management Systems course for the last eight years. The case study will provide readers with a detailed approach to the modeling process and a deeper understanding of data modeling. The Entity-Relationship Diagram The entity relationship diagram is a graphical representation of a conceptual structure of a problem domain being modeled.The ERD assists the database designer in identifying the data and the rules that will be represented and used in a database. The ERD is an implementation-independent representation of a problem domain and it facilitates communication between the end-user and the analyst. ERDs can be easily converted into a logical database structure that can be readily implemented in a particular commercial database management system. The basic components of the ERD are entities, properties of entities called attributes, and relationships between entities. Entities Entities are PRIMARY THINGS of a problem domain about which users need to record data.Ross (1988) provides a list of candidate entity types which could be included in the model. (1) People: humans who carry out some function Employees, Students, Customers (2) Places: sites or locations Cities, Offices, Routes (3) Things: tangible physical objects Equipment, Products, Buildings (4) Organizations Teams, Suppliers, Departments (5) Events: things that happen to some other entity at a given date and time or as in an ordered sequence Employee promotions, Project phases, Account payments (6) Concepts: intangible ideas used to keep track of business or other activities Projects, Accounts, Complaints 214 stepsAppendix A: A Practical Guide to Entity-Relationship Modeling These candidate entity types need to be evaluated against a particular domain being modeled. Some decision rules are discussed in a later section of this paper. Attributes Attributes are properties of entities or relationships. Entities have two types of properties: identi fying attributes and descriptive attributes. Identifying attributes uniquely determine each instance of an entity type. They are called entity identifiers or keys. For example, the attribute social security number would uniquely identify each member or instance of the entity type student.Descriptive attributes of student might include year, advisor, and grade point average. Each instance of an entity has a value for each attribute. Values for grade point average might include 2. 5, 3. 45, and 4. 0. Values for year might include 1991, 1992, 1993, and 1994. Only attributes that are meaningful in terms of modeling the problem under consideration are included in the ERD. For example, we would not include eye color in a student database. Relationships Relationships are another basic component of the ERD. A relationship is an association between or among things or entities.A relationship describes a meaningful interaction that needs to be remembered by the system. The degree of a relation ship indicates how many entities are participating in the relationship. A unary relationship describes an association of an entity with itself. A binary relationship, the most common instance, describes an association between two entities. A ternary (or n-ary ) relationship is an association between three or more entities. The ER methods that allow only unary and binary relationships are called binary models, while ER methods that allow any type of relationship are called n-ary models.For more thorough treatment of ternary relationships, see Jones and Song (1995, 1996) and Song and Jones (1995). Cardinality and Participation Constraints Cardinality is a constraint on the relationship between two entities. Specifically, the cardinality constraint expresses the maximum number of entities that can be associated with another entity via a relationship. For example, in a binary relationship (a relationship with two participating entities), we can have three possible cardinalities: oneto-o ne (1:1), one-to-many (1:N), or many-to-many (M:N).One-to-one cardinality says that, for entities customer and account, one customer can have at most one account and one account cannot be owned by more than one customer. One-to-many cardinality says that one customer can have many accounts, but one account cannot be owned by more than one customer. Many-to-many cardinality says that one customer can have many accounts and one account may be owned by many customers. 215 Appendix A: A Practical Guide to Entity-Relationship Modeling Participation is also a relationship constraint.Participation expresses the minimum number of entities that can be associated with another entity via a relationship. There are two values for participation: total or mandatory participation and partial or optional participation. If every instance of an entity must participate in a given relationship then that entity has total participation in the relationship. But if every instance need not participate in a g iven relationship then the participation of that entity in the relationship is partial. Given the relationship employee works for epartment, an employee has partial participation in that relationship if he or she need not work for a department. An employee has total participation in the relationship if he or she must work for at least one department. Similarly, a department has partial participation in the relationship if it can exist without having any employees. A department has total participation in the relationship if it must have at least one employee. Cardinality and participation constraints are business rules in the problem domain being modeled. These constraints represent the way one entity type is associated with another entity type.These constraints are also integrity constraints because they help to ensure the accuracy of the database. These constraints limit the ways in which data from different parts of the database can be associated. For example, let's say the cardin ality of the relationship between Customer and Account is one-to-one, as in Figure 1(a) below. If customer C1 is associated with account A3, then C1 cannot be associated with any other accounts and A3 cannot be associated with any other customers. 216 Appendix A: A Practical Guide to Entity-Relationship Modeling (a) One – to – One (1:1):One customer can have at most one account. One account cannot be owned by more than one customer. Customer 1 CA 1 Account ER Diagram C1 C2 C3 A1 A2 A3 Occurrence Diagram (b) One – to – Many (1:n): One customer can have many accounts. One account cannot be owned by more than one customer. Customer 1 C1 C2 C3 CA n A1 A2 A3 A4 A5 Account ER Diagram Occurrence Diagram (c) Many – to – Many (n:m): One customer can have many accounts. One account may be owned by many customers. Customer n C1 C2 C3 C4 C5 CA m A1 A2 A3 A4 A5 Account ER Diagram Occurrence Diagram Figure 1.CARDINALITY: The expression of the maximum numb er of entities that can be associated to another entity via a relationship. Occurrence Diagrams show the relationships between occurrences or instances of each entity. 217 Appendix A: A Practical Guide to Entity-Relationship Modeling Taxonomy in ER Modeling In an ER model, an entity is represented as a rectangle containing the name of the entity. The names of attributes are enclosed in an oval connected to the rectangle of the entity they describe. Attributes may be omitted from the diagram to avoid cluttering it and also in the early stages of development.Relationships are represented by diamonds between entities. The notation of the ERD, however, varies according to the modeling approach used. Binary models do not use the diamond to indicate a relationship, do not represent attributes of relationships, and do not allow ternary relationships, that is, relationships between three or more entities. Martin (1989), Bachman (1992), ERWin and IDEF1X (Bruce, 1992) use the binary modeling approach. Most text books use n-ary modeling, including Elmasri and Navathe (1994), Hawryszkiewycz (1991), Teorey (1994), Batini, Ceri and Navathe (1992), and McFadden and Hoffa (1994).A few notations are illustrated below. n Employee 1 Department a) Chen Employee Department b) Teorey n Employee 1 Department c) Elmasri ; Navathe Employee (0,1) works_for is_worked_for Employee works_for Employee p ——————–works_for Employee c has (1,n) Department d) MERISE Employee Department e) IE Department f) Bachman Department g) IDEF1X Department h) Shlaer & Mellor Figure 2. Various notations for ER Diagram representing â€Å"one employee works for zero or one department and one department has one or more employees†. 218 Appendix A: A Practical Guide to Entity-Relationship ModelingEach diagram in Figure 2 contains two entities: employee and department. In diagrams a, b, c, and d, the diamond indicates the relationship between the entities. T hese diagrams use n-ary modeling. Diagrams e through h are examples of binary modeling. They do not represent the relationship with the diamond shape. Instead, diagrams e, f, and h label the line between the entities with the relationship name. Attributes were not represented in the diagrams for simplicity. The various circles, lines, arrows, and letters on the diagram indicate cardinality and participation constraints.For a more complete treatment of various ER modeling methods, see Song, Evans, and Park (1995). ER Modeling How does one begin creating an entity relationship diagram? In this paper, we present step-by-step guidelines to build an ERD using n-ary modeling using Elmasri and Navathe's notation (see 2. c). In Table 1, we summarize a sequence of steps of database design using an ER model. Note that these steps are iterative. 1. Understand the problem domain. Analyze database requirements. †¢Write a summary specification in English, if not created yet. †¢What do w e need to store into the database? What queries and reports do we need to generate? †¢ What are important people, places, physical things, organizations, events and abstract concepts in the organization? 2. Design a conceptual schema by creating an ER diagram. (a) Identify entity types. Assign a singular noun to each entity type. (b) Identify relationships between (among) entities. Use a meaningful verb for a relationship name. (c) Draw an ERD without attributes. (d) Identify relationship cardinalities. †¢Mapping constraint (1:1, 1:N, N:M) †¢Participation constraint (Total, Partial) (e) Assign attributes to entity types and relationship types.Usually attributes come from nouns, adjectives or adverbs. (f) Select identifiers (primary keys) for entity types. †¢Weak entity: composite primary key. †¢Regular entity: choose/create a single attribute primary key. (g) Select the PKs of relationships. †¢If 1:1, then the PK of either side entity type may be select ed. †¢If 1:N, then the PK of N-side entity type must be selected. †¢ If M:N, then a composite PK consisting of PKs of two entity types must be used. †¢ If ternary, then a composite PK consisting of the PKs of at least two entity types.The actual PKs selected will vary depending on the cardinality. 3. Design a logical schema. (a) Translate the ERD into a relational schema 219 Appendix A: A Practical Guide to Entity-Relationship Modeling †¢If a relationship cardinality is likely to be changed; use stable method. †¢If a relationship cardinality is not likely to be changed; use mapped method. †¢ If a relationship cardinality is not likely to be changed and null values of foreign keys are significant; use mapped with total/partial method. (b) Check normalization (at least 3NF). (c) Create data dictionaries. A schema table †¢One table for each relation created in step (a) – Assign a domain type for each attribute. – Explain the meaning of a ttributes, if not intuitive. – Note other values such as range, null, PK, FK, indexed, source, owner (d) Do database prototyping & modify the design if necessary. (e) Summarize the design assertion (integrity, security). 4. Verify the design with users. Iterate the steps, if necessary. Table 1. Steps to DB Design Using ER Modeling First, it is important to study the problem domain at hand. Analyze database requirements.Write a summary paragraph for the problem domain, considering what data need to be stored and what queries and reports need to be processed. All the information necessary for the identified queries and reports must be included in the summary paragraph. Revise the summary paragraph considering database requirements. Second, from the summary paragraph, find nouns. They are candidates for entity types. To determine whether a noun should be designated as an entity, the following decision rules may be applied. Rule 1 Every entity type should be important in its own right within the problem domain.Rule 2 IF an object type (noun) has only one property to store THEN it is an attribute of another entity type ELSE it is an entity type. Rule 3 IF an object type has only one data instance THEN do not model as an entity type. Rule 4 IF a relationship needs to have a unique identifier 220 Appendix A: A Practical Guide to Entity-Relationship Modeling THEN model it as an entity type. The first three rules are used to evaluate object types or nouns, and the fourth rule is used to evaluate relationships or verbs. Example 1 Address is usually a property of another object type, like customer, vendor, or company.Its existence is less important and not meaningful in its own right within the problem domain. Address should be modeled as an attribute. Example 2 Suppose we are modeling the customers of a company and we want to include the city where each customer resides. If the name of the city is its only attribute, then, following Rule 2, model city as an attri bute not an entity. Similarly, consider the case of modeling employees and their departments. If the only important property of the department is its name, then Rule 2 tells us to model it as an attribute.However, if we need to store additional properties of each department such as projects or total sales, then we should consider modeling it as an entity. Example 3 Consider modeling the activities of a trucking company. Since there is only one instance of the trucking company, then, according to Rule 3, it is not necessary to represent it in our model as an entity. We note that it is not wrong to model this single instance noun as an entity type. We simply do not model it as an entity type at the conceptual level because it does not add any modeling power.We need the fourth rule because one fact can be stated in many different ways in English. In the fourth rule, distinguishing between entities and relationships depends on the function the component plays in the problem domain and h ow data will be stored about it. Example 4 Consider the three statements customer orders products, customer pays bills, and reviewer reviews papers. Even though orders and pays appear to represent relationships, we model them as entities since each instance would need a unique number for identification in real-world situations.Information would be stored in the database for each order and payment. Each review is not likely to need a unique identification number. Instead, we identify each review activity by a combination of Paper# and Reviewer#. Thus, by Rule 4, we model reviews as a relationship type. Once entities have been assigned, we proceed to identify relationship types between those entities. Verbs are useful candidates for relationships. The following question is useful for identifying relationships: â€Å"What sentences can be constructed of the form Entity Verb Entity? † For example, 221Appendix A: A Practical Guide to Entity-Relationship Modeling †¢Employee ha s children (Existence relationship) †¢Professor teaches students (Functional relationship) †¢Customer places order (Event relationship) Note that a relationship is not an action of a flow of data as in data flow diagrams. They are important interactions, between two or more entities, that need to be remembered by the system. In the above examples, we want to remember the facts that who is a child of which employee, which professor teaches which students, and which customer places which order. Also keep in mind that all relationships are bi-directional.We should be able to state the relationship in both directions. Expressing the relationships above in the opposite direction yields the following statements: †¢ Children belong to employee †¢ Students are taught by professor †¢ Order is placed by customer After an ERD has been built, the following rule can aid in validating the diagram. Rule 5 IF any verb refers to nouns which are not selected as entity types T HEN do not model it as a relationship type. If any verb in the ERD fails to follow Rule 5, then consider it again carefully before including it in the diagram.When entities and relationships have been identified, then the cardinality and participation constraints of the relationships can be analyzed. The following rules can help determine the cardinality and participation constraints for a given binary relationship. A B Rule 6 For each A, what is the maximum number of Bs that may be related to it? Rule 7 IF A can exist without being associated with a B THEN A has partial (optional) participation ELSE A has total (mandatory) participation. 222 Appendix A: A Practical Guide to Entity-Relationship Modeling Example 5 Consider the relationship Supplier Supplies Account.For each Supplier, what is the maximum number of Accounts that may be related to it? Let's say that in our problem domain, each Supplier may have many Accounts but each Account may have only one Supplier. By Rule 6, the ca rdinality constraint for Supplier:Account is 1:N or one to many. Figure 1 illustrates the cardinality constraints. Example 6 In determining the participation constraint of Supplier Supplies Account, we follow Rule 7: If Supplier can exist without being associated with Account, THEN Supplier has partial participation, ELSE Supplier has total participation.In our problem domain, Supplier may exist without being associated with Account. Therefore, Supplier has partial participation in the Supply relationship. However, since Account cannot exist without a Supplier; Account has total participation in the Supply relationship. Some basic naming conventions have been established to maintain accuracy and consistency in the database and to avoid redundancy. All entity names should be unique. Use singular nouns in the diagram for both entity and attribute names. Use verbs in the present tense for relationship names. Verbs should be meaningful.For example, avoid verbs like is, has, and do whene ver possible. Additionally, well-defined ERDs should satisfy the following basic rules: †¢ All entities and relationships should be connected. †¢ All entity names should be unique. †¢ Each entity must have at least one relationship. †¢ A relationship cannot be directly connected to another relationship. †¢ Every entity must have at least one unique attribute, which serves to identify each instance of that entity. Case Study The following example will illustrate our guidelines for modeling requirements of the problem domain with entity-relationship diagrams.Using the summary paragraph of the problem description below, we will progress through the steps described above. The nouns in the problem description appear in boldface and the verbs are italicized to aid in the following analysis. Summary Paragraph of Problem Description A database specialist wants to design a part of the database for a small drug store owner as follows: The owner wants to keep track of all the suppliers who supply anything to the store. For each supplier, the owner assigns a unique supplier number, and wants to keep the 223Appendix A: A Practical Guide to Entity-Relationship Modeling company name, address (number, street, city, state, zip), contact person's name, phone number, fax number, and a comment for each supplier. For each supply activity, an account is established to keep track of the date incurred, the total cost of the activity, due date for payment, outstanding balance after some payments, and any special comments related to the account. For each account, the owner may pay at several different times and in different ways (e. g. , cash, check, credit card).For each payment activity, the owner wants to keep the date of payment, amount of payment, method of payment (check: check number; credit card: credit card name, type, and number). Note that one supplier can supply many times and one payment can pay for several accounts of the same supplier. Entity Ana lysis After reading and understanding the problem statement, our first step is to identify entities for the ERD. To do that we examine the nouns in the problem statement. Nouns appear in boldface. We test each noun against our four criteria to determine whether or not it should be included as an entity type.Our first noun is owner. Recall that an entity type has more than one instance and more than one property. Since there is only one instance of owner, we do not model it as an entity type. Similarly, there is only one store, so we need not represent store as an entity type. The next noun, supplier, can be classified as an entity type. Several properties of supplier are listed in the problem statement. The statement also refers to more than one supplier. Therefore, according to Rules 1, 2, and 3, we model supplier as an entity.For each supplier, the owner wants to store the following properties in the database: supplier number, company name, contact person, address, phone number, f ax number, and comment. Each of these attributes except address has only one property to store so we model them as attributes. Address has its component properties number, city, state, and zip so one might be tempted to model it as an entity type. However, the role of address as a property of supplier supersedes the fact that address has properties of its own. In other words, address itself without supplier is not important in its own right.Therefore, by Rule 1, we model address as an attribute. Account is the next noun. Account has several properties to be stored in the database: date incurred, total cost, due date, account balance, and comments; and we will store information about numerous accounts. Therefore, we designate account as an entity. Its properties are modeled as attributes of account. Payment is clearly an entity, with multiple instances and various properties. The properties of payment: date of payment, amount of payment, and method of payment, are modeled as its attr ibutes.Cash, check, and credit card appear to be attributes of payment, but actually, they are not attributes themselves, but simply different values for the attribute method of payment. This distinction becomes clearer if we think about 224 Appendix A: A Practical Guide to Entity-Relationship Modeling storing data in the database. For each payment, one of the values cash, check, or credit card will be stored in the location containing data about the method of payment. Check number and credit card name, type and number may be modeled as attributes of Payment. Supplier Account Payment Figure 3. Entities to be included in the ERD.Relationship Analysis Our analysis of nouns in the problem statement has produced three entities: Supplier, Account, and Payment (Figure 3). Keep these entities in mind as we identify relationships between them. Let's examine the verbs in the problem statement as candidates for relationships in the diagram. Verbs appear in italics. Of the verbs in the problem statement: keep track, assigns, supply, established, and pay, only supply and pay are possible candidates for relationships between the entities account, supplier, and payment. Keep track and keep appear several times in the problem statement.These terms refer, not to a relationship between entities, but generally to storing data in the database. In other words, they are used to describe the problem domain, not an interaction that needs to be remembered by the system. Therefore, we do not model them as relationships. Established, in the statement an account is established, is an activity performed by the owner or the system itself. Similarly, owner assigns a unique supplier number reflects an activity by the owner. These two verbs do not represent relationships between any of our three entities. Thus, we are left with the verbs supply and pay.A supplier performs a supply activity. The result of a supply activity is an account. Therefore, a good candidate for the relationship betwee n supplier and account is supply. Stated in both directions, the relationship is Supplier supplies account and account is supplied by supplier. Rule 4 states that if a relationship needs to have a unique identifier, then model it as an entity. Each supply activity is unique, so we may be tempted to model supply as an entity. However, the data for each activity is stored using the entity account, so it is not necessary to create another entity which stores the same information.Each payment credits an account so pay is the relationship between payment and account. Expressing the relationship pay in both directions, we can say account is paid by payment and payment pays account. 225 Appendix A: A Practical Guide to Entity-Relationship Modeling Now we can draw the basic ERD (Figure 4). We include the entities Supplier, Account, and Payment, and the relationships Supply and Pay. Attributes may be added to the diagram at this point or omitted to avoid clutter. Supplier Supply Account Pay Payment Figure 4. ERD without attributes and constraintsAnalysis of Cardinality and Participation Constraints In order to identify the cardinality and participation constraints of each relationship in the ERD, we follow Rules 6 and 7 looking at the relationship first from the point of view of one entity and then from the other entity. In our ERD above, to determine the cardinality constraint of the relationship Supply, we begin by asking, â€Å"For each Supplier, what is the maximum number of Accounts that may be created? † From the problem statement, we know that one supplier can supply many times and an account is established for each supply activity.Viewing the relationship in the other direction, we ask, â€Å"What is the maximum number of Suppliers for which each Account may contain information? † From the problem statement we can assume that each account carries information for a single supplier, since accounts are established for individual supply activities. Th us, for each supplier, there may be many accounts and each account may have only one supplier. The relationship Supplier Supplies Account is a one-to-many relationship. The diagram is marked with a 1 on the side of the relationship Supply nearer to Supplier, and an N (for many) on the side nearer to Account (see Figure 5).To identify the cardinality of the relationship Payment Pays Account, we look at the relationship from both directions. We ask, â€Å"What is the maximum number of Payments we can accept for each Account? † The answer is clearly stated in the problem statement: For each account, the owner may pay at several different times and in different ways. From the opposite direction, â€Å"For each Payment, what is the maximum number of Accounts for which it may pay? † Again, we find the answer in the problem statement: One payment can pay for several accounts of the same supplier. In sum, each account 226Appendix A: A Practical Guide to Entity-Relationship Mod eling may receive many payments and each payment may pay for many accounts. Therefore, the relationship Payment Pays Account is many-to-many. This time, we mark our diagram with an M on one side of the relationship Pay and an N on the other side. (Note that the use of M or N is completely arbitrary. ) We go through a similar process to determine the participation constraint of each relationship, looking at the relationship from each direction. For the Supply relationship we ask, â€Å"Can a Supplier exist without generating Accounts? In the other direction, â€Å"Can an Account exist without having Suppliers supply merchandise? † The answers to these questions are not explicit in the problem statement. In a real world situation, the database designers would clarify questions like these with the owner. In this case, we will make assumptions from what we understand about the problem domain. Suppliers are generally fairly stable entities. A company maintains relationships with several regular suppliers regardless of whether they have outstanding accounts. On the other hand, an account is only created when a supplier supplies merchandise.Since suppliers can exist without having current accounts, Supplier has partial participation in the Supply relationship. Accounts, however, depend on suppliers for their existence. Thus, Account has total participation in the Supply relationship. To determine the participation of the entities Payment and Account in the Pay relationship, we ask, â€Å"Can a Payment exist without paying for an Account ? † and â€Å"Can an Account exist without receiving Payments against it? † A payment which pays for nothing is absurd. It cannot exist without an account. An account, however, may exist without receiving payments against it.Therefore, Payment has total participation and Account has partial participation in the relationship Pay. In representing the cardinality and participation constraints described above in our ERD, we will employ Elmasri and Navathe's (1994) notation. If an entity has partial participation in the relationship, then a single line is drawn on the line between that entity and the relationship. A double line indicates total participation. The cardinality constraint is represented by Look Across convention, while participation constraint is represented by Look Here convention.Figure 5 illustrates the final ERD with cardinality and participation constraints. 227 Appendix A: A Practical Guide to Entity-Relationship Modeling 1 Supplier Supply N Account M Pay N Payment Figure 5. ERD with cardinality and participation constraints. Errors in Modeling A common error that novice designers make is failing to recognize the boundaries of a problem domain. They fail to make a distinction between elements that comprise the content of the database and elements that are outside the scope of the database. For example, in the problem statement bove, a novice might want to model the verbs keep track or assigns or established as relationships (see Figure 6(a)). These verbs refer to implementing the database and not to its content. Keep track refers to storing data in the database, established refers to adding an instance of an entity to the database, and assigns refers to giving a value to an attribute of an entity. In deciding which elements to model, it is valuable to keep in mind the real world situation. Novice designers also frequently confuse entities with their attributes or properties, as in Figure 6(b).Occasionally, if properties are complex and play a significant role in the problem domain, then they may be modeled as entities. More often, however, properties of an entity should be modeled as attributes. In our problem statement, a novice user may decide to model address, a property of the entity supplier, as an entity. Modeling Address follows Rules 2 and 3 about identifying entities: it has more than one property and it has more than one occurrence. However, ad dress does not follow Rule1 in that it is not important in its own right.The role of address in the database is more accurate as an attribute of supplier, than as an entity with its own relationships. Other errors are modeling indirect or redundant relationships and inappropriately modeling object types as relationships rather than as entities. Given our problem statement, one may be tempted to model the relationship Payment Pays Supplier as in Figure 6(c) or Supplier Pays Account as in Figure 6(d) rather than Payment Pays Account. Figure 6(c) represents the association between payment and account indirectly. This indirect relationship can only exist after we have all the direct 228Appendix A: A Practical Guide to Entity-Relationship Modeling relationships as in Figure 5. In this case, the indirect relationship simply becomes redundant. Without the direct relationships, the indirect relationship cannot be added, because it cannot explain how a particular payment is distributed to mu ltiple accounts. Figure 6(d) represents the relationship Pay rather than the entity Payment. In either of these two cases, it is difficult to explicitly represent the fact that one payment can pay for several accounts of the same supplier. We can only tell implicitly by reading the check number for the various payments.If the payment is made in cash, there is no way to identify that it paid for more than one account. If the representation used in Figure 6(d) is used, then the attributes related to payments: date of payment, amount of payment, and method of payment, are now attributes of the relationship Pay. This representation can add unnecessary complexity to the model. Ordinarily, a relationship is uniquely represented by the identifiers of one or more of the entities which participate in it. If the relationship includes a time-dependent attribute like date of payment, then that attribute must also be included in the primary key for that relationship.Additionally, instances of da te of payment and amount of payment will require redundant representation because they will have to be included for each account covered by a payment. Finally, in business practice, each payment activity usually requires a unique identifier. Therefore, following Rule 4, it is more appropriate to model payment as an entity than as a relationship. As an entity, the representation is more straightforward and less likely to include redundant or inaccurate information. 229 Appendix A: A Practical Guide to Entity-Relationship Modeling a) Selection of wrong verb as relationship Owner (b) Attribute as entity Supplier Located_at Address Keeps_track Payment (c) Indirect relationship Payment Pays Supplier Establishes Account (d) Payment as relationship instead of entity Establishes Supplier Pays Account Figure 6. Errors in ERD Modeling. Limitations of Guidelines and Rules Two limitations of our guidelines are that they don't account for incomplete requirements analysis or for ambiguity in the problem description. If the problem description is incomplete, then the resulting analysis based on this approach will also be incomplete.We assume that the analysis is complete. If the problem specification is modified, the analysis and resulting ERD should be modified as well. In English, one concept can be represented in many different ways. For example, we can say that customer orders products or customer places an order to buy products. Order is used 230 Appendix A: A Practical Guide to Entity-Relationship Modeling as a verb in the first sentence and as a noun in the second. We minimize this problem by adopting Rule 4, which states that if a verb needs to have a unique identifier, we model it as an entity type rather than a relationship type.Conclusion We have discussed a set of decision rules which are useful in building ERDs and have illustrated the application of these rules using a single example. ERD constructs discussed here include Entities, Relationships, Attributes, Ca rdinality constraints and Participation constraints. To simplify our discussion, we didn't include other constructs such as Weak Entity, Ternary Relationship, and Generalization/ Specialization. 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