SQL Server Advanced Data Types attempts to demystify the complex data types that are available to developers in modern versions of SQL Server. Over the last couple of years, I have noticed that many SQL developers have heard of each of the complex data types available in SQL Server but often avoid using them, as they are not sure how these are best utilized. This has led to suboptimal solutions being developed, such as an incident that I recently experienced in which a very good and seasoned SQL developer implemented complex hierarchical logic using self joins, because he did not feel confident implementing the HierarchyID data type. That inspired me to write this book—to help SQL and other developers responsible for writing T-SQL, as part of their applications, to better understand the complex data types available in SQL Server and give them the confidence to use these complex structures appropriately. The book starts by exploring the simple, conventional data types that are available in SQL Server and reminds readers why making the right choices about data types can be so important. The book then moves on to offer in-depth discussions about the complex data types in SQL Server, namely, XML, JSON, HierarchyID, GEOGRAPHY, and GEOMETRY. Many of the code examples in the book are based on real-world problems and solutions that I have encountered in my time as an SQL Server consultant in London. Many of the code examples in this book use the WideWorldImporters sample database. The GitHub repo for this database can be found at github.com/Microsoft/sql-server-samples/tree/master/samples/ databases/wide-world-importers and the .bak file can be downloaded from github. com/Microsoft/sql-server-samples/releases/download/ wide-world-importers-v1.0/WideWorldImporters-Standard.bak.