Modern Database Management
13th Edition
ISBN: 9780134773650
Author: Hoffer
Publisher: PEARSON
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Chapter 2, Problem 2.34PAE
The Is Married To relationship in Figure 2-12a would seem to have an obvious answer in Problem and Exercise is, until time plays a role in modeling data. Draw a data model for the PERSON entity type and the Is Married TO relationship for each of the following variations by showing the appropriate cardinalities and including, if necessary, any attributes:
- All we need to know is who a person is currently married to, if anyone. (This is likely what you represented in your answer to problem and Exercise 2-33d.)
- We need to know who a person has ever been married to, if anyone.
- We need to know who a person has ever been married to, if anyone, as well as the date of their marriage and the date, if any, of the dissolution of their marriage.
- The same situation as in c, but now assume (which you likely did not do in c) that the same two people can remarry each other after a dissolution of a prior marriage to each other.
- In history, and even in some cultures today, there may be no legal restriction on the number of people to whom one can be currently married. Does your answer to part c of this Problem and Exercise handle this situation or must you make some changes (if so, draw a new ERD).
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The model above needs some improvement. Where you can apply all the normalization rules to attributes. Furthermore, you also need to explain entities and relations between them, and the purpose of attributes by showing why and how they exist ?.
Create an Entity-Relationship Model to represent the data requirements of the problem given below. Specify the cardinalities of relationships and all-important constraints. Also mention the assumptions if you have made any.
A person can be an employee, alumnus or a student. For person P_id (identifier), date of birth, gender and contacts are stored. Person can have more than one contact numbers and there are no other types of person that exists. An instance of person can belong to more than one type. Date hired and salary is the unique attributes of employee. For alumnus degree is required to be stored that comprises of year and designation. Major department is the attribute of student. A student can be a graduate student or an undergraduate student but not both at the same time. No other type of student exists. For graduate student test score is stored and for undergraduate student class standing is stored. Employee can be faculty, staff or others but not both at the same time. For…
Create an Entity-Relationship Model to represent the data requirements of the problem given below. Specify the cardinalities of relationships and all-important constraints. Also mention the assumptions if you have made any. [20 Marks]
A person can be an employee, alumnus or a student. For person P_id (identifier), date of birth, gender and contacts are stored. Person can have more than one contact numbers and there are no other types of person that exists. An instance of person can belong to more than one type. Date hired and salary is the unique attributes of employee. For alumnus degree is required to be stored that comprises of year and designation. Major department is the attribute of student. A student can be a graduate student or an undergraduate student but not both at the same time. No other type of student exists. For graduate student test score is stored and for undergraduate student class standing is stored. Employee can be faculty, staff or others but not both at the same…
Chapter 2 Solutions
Modern Database Management
Ch. 2 - Define each of the following terms: entity type...Ch. 2 - Match the following terms and definitions....Ch. 2 - Contrast the following terms: stored attribute;...Ch. 2 - Prob. 2.4RQCh. 2 - Prob. 2.5RQCh. 2 - Prob. 2.6RQCh. 2 - State six general guidelines for naming data...Ch. 2 - Prob. 2.8RQCh. 2 - Prob. 2.9RQCh. 2 - State three conditions that suggest the designer...
Ch. 2 - List the four types of cardinality constraints,...Ch. 2 - Give an example, Other than those described in...Ch. 2 - What is the degree of a relationship? List the...Ch. 2 - Give an example (Other than those described in...Ch. 2 - Give an example of each of the following, other...Ch. 2 - Give an example of the use of effective (or...Ch. 2 - State a rule that says when to extract an...Ch. 2 - Prob. 2.18RQCh. 2 - In addition to explaining what action is being...Ch. 2 - For the Manages relationship in Figure 2-12a,...Ch. 2 - Explain the distinction between entity type and...Ch. 2 - Why is it recommended that every ternary...Ch. 2 - A cellular operator needs a database to keep track...Ch. 2 - Prob. 2.24PAECh. 2 - Answer the following questions concerning Figure...Ch. 2 - Prob. 2.26PAECh. 2 - You may have been assigned a CASE or a drawing...Ch. 2 - Consider the two E-R diagrams in Figure 2-25 Q,...Ch. 2 - Prob. 2.29PAECh. 2 - Are associative entities also weak entities? Why...Ch. 2 - Because Visio does not explicitly show associative...Ch. 2 - Figure 2-26 shows a grade report that is mailed to...Ch. 2 - Prob. 2.33PAECh. 2 - The Is Married To relationship in Figure 2-12a...Ch. 2 - Figure 2-27 represents a situation of students who...Ch. 2 - Figure 2-28 shows two diagrams (A and B), both of...Ch. 2 - Prob. 2.37PAECh. 2 - Review Figure 2-8LQ and Figure 2-22. Identify any...Ch. 2 - Prob. 2.39PAECh. 2 - Prob. 2.40PAECh. 2 - Prob. 2.41PAECh. 2 - Prob. 2.42PAECh. 2 - Prob. 2.43PAECh. 2 - Prob. 2.44PAECh. 2 - Prob. 2.45PAECh. 2 - Prob. 2.46PAECh. 2 - Prob. 2.47PAECh. 2 - Prob. 2.48PAECh. 2 - Draw an ERD for the following situation. (State...Ch. 2 - Prob. 2.50PAECh. 2 - Prob. 2.51PAECh. 2 - Review your answer to Problem and Exercise 2-49 if...
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