Databases and Information Management Information Systems Managing the
Databases and Information Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. Chapter 6 (Part 2)
FIGURE 6 -5 The select, join, and project operations enable data from two different tables to be combined and only selected attributes to be displayed. Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. Three Basic Operations of Relational DBMS
Data definition capability: Specifies structure of database content, used to create tables and define characteristics of fields Data dictionary: Automated or manual file storing definitions of data elements and their characteristics Data manipulation language: Used to add, change, delete, retrieve data from database § § Structured Query Language (SQL) Microsoft Access user tools for generation SQL Many DBMS have report generation capabilities for creating polished reports (Crystal Reports) Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. Capabilities of DBMS
Data Dictionary Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. MICROSOFT ACCESS DATA DICTIONARY FEATURES Microsoft Access has a rudimentary data dictionary capability that displays information about the size, format, and other characteristics of each field in a database. Displayed here is the information maintained in the SUPPLIER table. The small key icon to the left of Supplier Number indicates that it is a key field. FIGURE 6 -6 Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon
Querying FIGURE 6 -7 Illustrated here are the SQL statements for a query to select suppliers for parts 137 or 150. They produce a list with the same results as Figure 6 -5. Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. EXAMPLE OF AN SQL QUERY
Querying Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. AN ACCESS QUERY Illustrated here is how the query in Figure 6 -7 would be constructed using Microsoft Access query building tools. It shows the tables, fields, and selection criteria used for the query. FIGURE 6 -8 Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon
Designing Database The design process identifies relationships among data elements (fields)/tables and the most efficient way of grouping fields in specific tables The design process also identifies redundant data elements To group data elements in normalization process is done small and related tables, Referential integrity: Referential integrity is a property of data which, when satisfied, requires every value of one column of a table to exist as a value of another column in a different table Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. To design a database you must understand the relationships among data and tables, the type of data in tables,
Normalization • Normalization NORMALIZED TABLES CREATED FROM ORDER Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. AN UNNORMALIZED RELATION FOR ORDER
Entity-Relationship Diagram • Entity-relationship diagram (ERD) Illustrates relationships between entities AN ENTITY-RELATIONSHIP DIAGRAM This diagram shows the relationships between the entities SUPPLIER, PART, LINE_ITEM, and ORDER that might be used to model the database in Figure 6 -10. Management Information Systems: Managing the Digital Firm, 12 e Authors: Kenneth C. Laudon and Jane P. Laudon Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd. Used by database designers to document the data model
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