For those who are working with SQL systems - or preparing to do so - this book offers information organized by use rather than by feature. Therefore, readers can turn to specific business problems and learn how to solve them with the appropriate SQL features. In particular, the book focuses on the real-world challenges of dealing with legacy systems, inherited problematic code, dirty data, and query tuning for better performance. The following important topics are addressed: * Finding and fixing dirty data with LIKE, BETWEEN, and LOCATE * Managing multiples and other complex data problems with ROWID, SIMILAR, GROUP BY, and HAVING * Handling the multiple display formats of dates * Translating values to expand compressed codes with CASE, DECODE, point functions, UNION, and subqueries * Manipulating numbers, including using auto-numbering mechanisms, finding the high value, locating every Nth, and more. * Tuning queries for enhanced performance, focusing on indexes and the optimizer * Comparing vendors system catalogs and system functions * Using SQL to generate SQL for cleanup and permission scripts as well as creating test data A business-based working database serves as a running e