ch05_v8_notes

ch05_v8_notes - 1 Essentials of Business Information...

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Essentials of Business Information Systems, 8E Chapter 5 Foundations of Business Intelligence: Databases and Information Management Information is becoming as important a business resource as money, material, and people. Just because a company compiles millions of pieces of data doesn’t mean it can produce information that is of any use to its employees, suppliers, and customers. Successful businesses realize the competitive advantage they gain by producing useful information, not just data. 5.1 The Database Approach to Data Management Why should you learn about organizing data? Because it’s almost inevitable that someday you will establish or at least work with a database of some kind. Digital databases make it easy, fast, and efficient to relate pieces of data together to compile useful information. As with anything else, understanding the lingo is the first step to understanding the whole concept of managing and maintaining information. Entities and Attributes An entity is basically any person, place, thing, or event on which we maintain information. Each characteristic or quality describing an entity is called an attribute. In the table below, each column describes a characteristic ( attribute ) of John Jones’ (who is the entity ) address. First Name Last Name Street City State Zip Telephone John Jones 111 Main St Center City Ohio 22334 555-123-6666 Organizing Data in a Relational Database A relational database stores data in tables. The data are then extracted and combined into whatever form or format the user needs. The tables are sometimes called files, although that is actually a misnomer, since you can have multiple tables in one file. Data in each table are broken down into fields. A field, or column, contains a single attribute for an entity. A group of fields is stored in a record or tuple (the technical term for record). Figure 5-1 shows the composition of a relational database table. 1
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Figure 5-1: A Relational Database Table. Each record requires a key field , or unique identifier. The best example of this is your social security number: there is only one per person. That explains in part why so many companies and organizations ask for your social security number when you do business with them. In a relational database, each table contains a primary key , a unique identifier for each record. To make sure the tables relate to each other, the primary key from one table is stored in a related table as a foreign key . For instance, in the customer table below the primary key is the unique customer ID. That primary key is then stored in the order table as the foreign key so that the two tables have a direct relationship. Customer Table Order Table Field Name Description Field Name Description Customer Name Self-Explanatory Order Number Primary Key Customer Address Self-Explanatory Order Item Self-Explanatory Customer ID Primary Key Number of Items Ordered Self-Explanatory Order Number Foreign Key Customer ID Foreign Key Suppose you decide to create a database for your newspaper delivery business. In order
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This note was uploaded on 11/27/2010 for the course IS 3300 taught by Professor Pettey during the Spring '08 term at Troy.

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ch05_v8_notes - 1 Essentials of Business Information...

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