Database Systems: Design, Implementation, & Management
12th Edition
ISBN: 9781305627482
Author: Carlos Coronel, Steven Morris
Publisher: Cengage Learning
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Expert Solution & Answer
Chapter 4, Problem 13RQ
Explanation of Solution
Composite entity:
A composite entity is normally used to convert M: N relationships into 1: M relationships. It is also referred as “bridge entity”, which has a primary key (PK) composed of multiple attributes.
- The PK attributes are inherited from the entities, which it associates to one another.
Usage of composite entity in ERD:
In the Entity Relationship Management (ERM), an M: N relationship is effective at the conceptual level. But when implementing the ERM in a relational
Example:
Consider the entities CLASS and STUDENT with M: N relationship defined by following business rules:
- A student can take several classes...
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Chapter 4 Solutions
Database Systems: Design, Implementation, & Management
Ch. 4 - Prob. 1RQCh. 4 - What is a strong (or identifying) relationship,...Ch. 4 - Prob. 4RQCh. 4 - Suppose you are working within the framework of...Ch. 4 - Prob. 6RQCh. 4 - Prob. 7RQCh. 4 - Discuss the difference between a composite key and...Ch. 4 - What two courses of action are available to a...Ch. 4 - Prob. 11RQCh. 4 - Discuss two ways in which the 1:M relationship...
Ch. 4 - Prob. 13RQCh. 4 - Prob. 14RQCh. 4 - Briefly, but precisely, explain the difference...Ch. 4 - What are multivalued attributes, and how can they...Ch. 4 - Prob. 17RQCh. 4 - Prob. 18RQCh. 4 - What two attributes must be contained in the...Ch. 4 - Describe precisely the composition of the...Ch. 4 - Prob. 21RQCh. 4 - Prob. 1PCh. 4 - Create a complete ERD in Crows Foot notation that...Ch. 4 - Prob. 4PCh. 4 - Prob. 5PCh. 4 - Prob. 6PCh. 4 - Prob. 7PCh. 4 - Prob. 8PCh. 4 - Prob. 9PCh. 4 - Prob. 10PCh. 4 - Prob. 11C
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- Explain ENTITY EXTRACTION AND ER DIAGRAMarrow_forwardWhat is the purpose of entity-relationship diagrams? What sort of symbol is used to depict a connection, and how does it work? What exactly does the phrase "associative entity" imply and what does it mean? Give an example.arrow_forwardWhat is the precise definition of a weak entity type? What is the undisclosed information? Could you please provide an example? What is the definition of alternative specialization?What is my representation on the Entity-Relationship (ER) diagram? Please provide more context or information about the example and diagram you are referring to. What subject or topic is this related to?arrow_forward
- Given the ER diagram above, answer the following questions: a. Name an entity type that has more than 2 relationships. b. Name one ket attribute and the entity type it belongs to. c. Name one one-to-one relationship and the entity types it relates. d. Name one many-to-many relationship and its entity types. e. Name one relationship attribute. f. What is the cardinality of relationship ‘employs’? g. What is the cardinality of relationship ‘textUsed’? h. Name one weak entity type i. Does it have a partial key? If yes, name it. ii. Name its identifying entity type iii. Name its identifying relationship Question 2 A bank provides services to customers. The banks is identified by its code and has a name and an address. The bank has several branches. A branch is identified by its code that is unique for a given bank. The branch name and address are also stored in the database. Customers deal with the bank through the bank branches. So, a customer belongs to a specific bank branch. Customers…arrow_forwardFor each entity, there needs to be an indication of whether it is one-to-one, one-to-many or many-to-many relationship. Here are the answers I have but I could use more guidance with it. I struggle with this type of question. BOOK and BOOK COPY (1:1) COURSE and COURSE-SECTION (M:N) COURSE-SECTION and ROOM (M:1) INSTRUCTOR and COURSE (1:M) ROOM and INSTRUCTOR (M:1)arrow_forward(a) Explain carefully four ways in which the diagram fails to model the intended world. In each case make sure you contrast the actual meaning with the intended meaning. (b) Give an entity-relationship diagram, still using two entity types, which correctly models the intended world. (c) Give a database schema (including primary keys) for the ER diagram which you have given in the previous part. (d) Is there any part of the ER diagram which is not captured in the schema? How might this aspect be captured in the final database?arrow_forward
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