How does it work?

Let’s say you have a Task List (Parent List A), a User Information list (Lookup List B), and a Project List (Lookup List C). Your manager has asked you to provide a quick status on all tasks including the task name, assigned user name and the user’s email address, the associated project name and project status. Using the Cross List Web Part and lookup fields, you can choose the data you need from the Task List as well as any data you need from the Project List and the User Information List (see diagram below) - not just the data from the lookup columns.

Why did we build it?

Organizations use SharePoint today to build quick and efficient collaboration portal web sites. As the use of SharePoint grows, IT is being asked to build new applications as an alternative to the traditional database, with the ability to integrate with legacy data to provide a single point of information access. One of the main attractions of SharePoint is the ability to quickly create standard Lists to support different types of tasks. Developers that are familiar with classic database design are using "lookup" fields within lists to architect relational structured data instead of using a flat data structure. SharePoint does not provide a capability to display data from multiple joined lists, even when look up fields are used as index keys into a foreign list.