Summary

Tables are at the heart of relational databases in general and SQL Server in particular. In this chapter, we looked at the internal storage issues of various data types, in particular comparing fixed- and variable-length data types. We saw that SQL Server 2005 provides multiple options for storing variable-length data, including data that is too long to fit on a single data page, and you saw that it's simplistic to think that using variable-length data types is either always good or always bad. SQL Server provides user-defined data types for support of domains, and it provides the IDENTITY property to make a column produce auto-sequenced numeric values. You also saw how data is physically stored in data pages, and we queried some of the metadata views that provide information from the underlying (and inaccessible) system tables. SQL Server also provides constraints, which offer a powerful way to ensure your data's logical integrity.