chap006 - Chapter 6 Relational Database Design: Converting...

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Chapter 6 Relational Database Design: Converting Conceptual REA Models to Relational Databases Review Questions R1. What type of data does each record in an event table contain? Event data tables are much like expanded information age journals; they do not require the summarization and loss of detail required to record traditional accounting transactions. All the detailed documentation of business activity data is available in the event data stores. Each record in an event data table contains documentation of a particular business event. R2. What type of data does each record in a resource table contain? Each resource data table includes data describing a corporate resource. Each record in a resource table contains data about one particular instance of a resource. R3. What type of data does each record in an agent table contain? Each agent data table provides information about an internal or external person or entity category. Each record in an agent table contains data about one particular instance of an agent. R4. What is the purpose of a foreign key? Foreign keys are key attributes of an object that are posted into another object table. The sole purpose of foreign keys is to link tables so the tables can be used collectively to store business data and to generate useful information. R5. Does every table in a relational database contain a foreign key? Explain. No. Foreign keys can only be posted into tables for which the entity’s participation in a relationship has a maximum of 1. Most resource and agent tables will not contain foreign keys because they can participate many times in the relationships with related events. Sometimes they may have foreign keys representing relationships with other agents or resources (e.g. customer may have a salesperson identifier posted as a foreign key to represent the one salesperson that is assigned responsibility for the customer). Solutions Manual to accompany Dunn, Enterprise Information Systems: A Pattern Based Approach, 3e 69
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Chapter 6 R6. What tables are needed to perform a recording information process? The recording process updates the event table and any table in which relationship data for the event is stored. For example, to record a sale event, a record must be added to the sale table. If all relationships in which sale participates are implemented with foreign keys posted into the sale table, then the addition of that record is all that need be done. However, if some of the relationships are represented with separate tables, then records must be added to those tables too. For example, if the relationship between sale and inventory type is many-to-many, and the sale involved three inventory items, then three records must be added to the stockflow sale-inventory relationship table in addition to the one record added to the sale table. Note that typically no data needs to be added to the inventory type or to the agent tables to record an event. R7. What tables are needed to perform a maintenance information process?
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This note was uploaded on 01/17/2011 for the course INFO SYSTE 115 taught by Professor Baker during the Spring '10 term at Strayer.

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chap006 - Chapter 6 Relational Database Design: Converting...

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