Book Image

Data Analysis Using SQL and Excel - Second Edition

By : Gordon S. S. Linoff
Book Image

Data Analysis Using SQL and Excel - Second Edition

By: Gordon S. S. Linoff

Overview of this book

Data Analysis Using SQL and Excel, 2nd Edition shows you how to leverage the two most popular tools for data query and analysis—SQL and Excel—to perform sophisticated data analysis without the need for complex and expensive data mining tools. Written by a leading expert on business data mining, this book shows you how to extract useful business information from relational databases. You'll learn the fundamental techniques before moving into the "where" and "why" of each analysis, and then learn how to design and perform these analyses using SQL and Excel. Examples include SQL and Excel code, and the appendix shows how non-standard constructs are implemented in other major databases, including Oracle and IBM DB2/UDB. The companion website includes datasets and Excel spreadsheets, and the book provides hints, warnings, and technical asides to help you every step of the way. Data Analysis Using SQL and Excel, 2nd Edition shows you how to perform a wide range of sophisticated analyses using these simple tools, sparing you the significant expense of proprietary data mining tools like SAS.
Table of Contents (18 chapters)
Free Chapter
1
Foreword
17
EULA

CHAPTER 14
Performance Is the Issue: Using SQL Effectively

This chapter differs from the earlier chapters by shifting the focus from functionality to performance. The subject of performance can be highly database specific. Fortunately (and perhaps surprisingly), some general rules and considerations apply to most if not all databases. Some of these rules are based on general principles of how database engines are designed; others are based on how SQL is written; and still others on how the data is represented in the database. This chapter covers these general principles rather than database-specific optimizations.

The power of SQL arises from several factors. First, SQL can express many important data manipulations needed for analysis—the use of common table expressions and subqueries gives the language a lot of power. Second, the database engine optimizes the queries for available hardware and data. This optimization is very important: The same SQL query that runs on a...