XPath Data Types

It isn't always possible to map one data type to another when you're talking about XDR schema, XPath, and SQL Server 2000. Each of these entities has its own data types, and many of these data types have no counterpart in the other entities. A very important example of this is that XPath has no integer data type, while SQL Server has several different kinds. XPath has only number, string, and Boolean data types, but even then, its number data type doesn't map to SQL Server's closest match, float(53). Float(53) does not completely follow the IEEE 754 double-precision floating-point specification, whereas the XPath number data type does.

I refer you to the section "Data Type Coercions" in Chapter 5, "Creating XML Views with XDR Schemas," to see how XDR data types map to SQL Server data types. We'll see how XDR schema data types map to XPath data types in just a minute.