Chapter 3 Building an XML model
Identity constraints enable you to indicate that element values must be unique within their specified scope.
There are three kinds of identity constraints: unique, key and keyRef.
Each identity constraint has two specific attributes: selector and field.
In a schema, an identity constraint is declared with its corresponding tag: <unique>, <key> or <keyRef>.
Identity constraints are only available in a model targeted with XSD.
| Copyright (C) 2005. Sybase Inc. All rights reserved. |
| |