Chapter 3 Building an XML model

Defining a unique constraint

A unique constraint specifies that an element or an attribute value (or set of values) must be unique or null within a specified scope.

For example:

Generated schema:

The UNIQUENUM unique constraint, defined on the project element, specifies that the numEmployee attribute must be unique or null within the employee element

To display a unique property sheet, double-click its name or its icon in the Browser tree view.

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