There has never been a standard for storing and processing hierarchical data. Over the years, multiple approaches have emerged. Oracle provides the START WITH...CONNECT BY PRIOR syntax. Joe Celko even wrote an entire book on the subject. With SQL Server 2008, the new hierarchyid data type offers an easily understand and implemented approach to storing hierarchical data. It can be implemented with either breadth-first or depth-first indexing for navigating the hierarchy, which makes it a flexible and viable solution for handling hierarchical data while delivering good performance. To illustrate the usefulness of the hierarchyid data type, this session will tackle a problem of great financial and business significance to the manufacturing industry: Bill Of Materials (BOM). All of the various forms of the Bill of Materials (engineering, manufacturing, sales, service) are comprised of hierarchical data. Individual parts are assembled into units called subassemblies. Subassemblies and individual parts are assembled into finished goods. The BOM problem is explained in detail so that the application developer thoroughly understands the requirements. Next, the audience is shown how to take the requirements and transform them into a logical hierarchical model. Finally, the audience is shown how to take the logical design and use SQL Server's hierarchyid to implement the physical design. Implementing a BOM solution with SQL Server 2008 provides the developer with the skills to solve similar problems such as modeling an organizational structure, a set of tasks in a project, or web site navigation graphs.