SharePoint 101 F. Server side dev ~ Accessing List Data through CAML and LINQ to SharePoint

When you are server-side in the context of a site collection, the typical way to query for data in list is to use SharePoint's custom XML query language: CAML. A more modern approach is to use the SPMetal + LINQ to SharePoint combination.

##CAML: the Collaborative Application Markup Language

• CAML is another term for all the XML schemas used to provision content in a SharePoint context
  • (e.g. all modules in Elements.xml files follow a CAML schema)
• In the context of SharePoint list queries, CAML serves as an abstraction over SQL queries to the SharePoint database

References:

• Office Dev Center - Introduction to Collaborative Application Markup Language (CAML)

##Building your first CAML query

• The SPQuery API

• Using a CAML builder tool to debug your queries

  • The most popular is U2U's CAML Builder: http://www.u2u.be/Software

• Use a Recursive Scope, otherwise you won't find items in folders

• How to avoid excessive database calls when dealing with large item lists

  • Don't forget your ViewFields, otherwise each SPListItem field access will hit the database
  • Avoid looping through all SPListItems in a large SPListItemCollection, prefer using SPListItemCollection.GetDatatable()

Reference:

• CAML Query Schema

A friendlier alternative: SPMetal / LINQ-to-SharePoint

• SPMetal is a command line tool that comes with SharePoint Foundation that can generate C# entity classes by reverse engineering the contents of your SharePoint sites
• With the DataContext generated by SPMetal, you can use LINQ to query over the generated entity classes and their associated list data source.

References

• MSDN - Managing Data with LINQ to SharePoint
• MSDN - SPMetal Reference