Often times there can 4,5,6 different ways to write an SQL query and get the same results back. What makes one better than any of the others, and is there any ones that are always better, or always worse? Sometimes rewriting 1 predicate in an SQL statement can cause optimization to change. This presentation breaks down many examples of query rewrites and how they can affect performance and optimization. Being strong in SQL is a great skill when it comes to performance and tuning of queries.
Tony Andrews has more than 25 years’ experience in the development of relational database applications. Most of this time, he has provided development and consulting services to Fortune 500 companies and government agencies. Tony has written literally thousands of queries and programs during his development years, and has also served as a database analyst. For the last 10 years, Tony has been splitting his time between performance and tuning consulting engagements along with training. His main focus is to teach today’s developers the ways of RDMS application design, development and SQL programming -- always with a special emphasis on improving performance. He is a current IBM Champion, and regular speaker at many regional user groups, IDUG NA, and IDUG EMEA. He is also the author of a book for developers titled ‘DB2 SQL Tuning Tips for z/OS Developers’.