
Defining identity constraints
Syntax | Description  | 
/book/chapter[2]/section[3]  | Selects the third section in the second chapter of  | 
  | the book  | 
employee[@dept=”doc”]  | Selects all the employee child elements of the  | 
  | context node with a dept attribute set to doc  | 
employee[@dept=”doc”][3]  | Selects the third employee child element of the  | 
  | context node with a dept attribute set to doc  | 
employee[3][@dept=”doc”]  | Selects the third employee child element of the  | 
  | context node only if it has a dept attribute set to  | 
  | doc  | 
chapter[title]  | Selects the chapter child elements of the context  | 
  | node with at least one title child element  | 
chapter[title=”About this  | Selects the chapter child elements of the context  | 
book”]  | node with at least one title child element with a  | 
  | text content set to About this book  | 
employee[@numEmployee and  | Selects all the employee child elements of the  | 
@dept]  | context node with the numEmployee and dept  | 
  | attributes  | 
text()  | Selects all the child nodes of the text context  | 
  | node  | 
  | 
  | 
Defining selector general properties
The General page of a selector property sheet displays the following properties:
Property | Description  | 
XPath  | An XPath expression relative to the parent element being  | 
  | declared. It identifies the child elements to which the identity  | 
  | constraint applies  | 
Stereotype  | |
  | without changing its structure. It can be predefined or user-  | 
  | defined  | 
ID  | ID of the selector. Its value must be of type ID and unique within  | 
  | the model containing the selector  | 
  | 
  | 
To display a selector property sheet:
1Type an XPath expression in the Selector groupbox of an identity constraint (unique, key or keyRef) property sheet.
72  | PowerDesigner  |