XML schema collections

Chapter 15 DBMS-Specific Features

XML schema collections

An XML schema collection provides the following:

Validation constraints - Whenever a typed xml instance is assigned to or modified, SQL Server validates the instance.
Data type information about the instance data - Schemas provide information about the types of attributes and elements in the xml data type instance. The type information provides more precise operational semantics to the values. For example, decimal arithmetic operations can be performed on a decimal value, but not on a string value. Because of this, typed XML storage can be made significantly more compact than untyped XML.

PowerDesigner models XML schema collections as extended objects with a stereotype of <<XMLSchemaCollection>>.

Creating an XML schema collection

You can create a XML schema collection in any of the following ways:

Select Model→XML Schema Collection Objects to access the List of XML Schema Collections, and click the Add a Row tool
Right-click the model or package in the Browser, and select New→XML Schema Collection

XML schema collection properties

You can modify an object's properties from its property sheet. To open a XML schema collection property sheet, double-click its diagram symbol or its Browser entry in the XML Schema Collection Objects folder.

The following extended attributes are available on the Microsoft tab:

Name	Description
Owner	Specifies the name of a user, role, or schema as the owner of the schema collection. Scripting name: Owner
XML model	Specifies a PowerDesigner XML model to link to the schema. Scripting name: XMLModel
Content	Specifies the content of the xml schema. By default this field contains the %xmlModelContent% template, which represents the content of the linked XML model. Scripting name: Content