XML Schema field element
Complete XML Schema Reference Definition and Usage
field element specifies XPath expression, the value (or a value) to specify the expression used to define the identity constraint (unique, key and keyref elements).
Element Information
- Parent element: key, keyref, unique
grammar
<field
id=ID
xpath=XPath expression
any attributes
>
(annotation?)
</field>
id=ID
xpath=XPath expression
any attributes
>
(annotation?)
</field>
(? Sign declares in the field element, which can occur zero or one time.)
| 属性 | 描述 |
|---|---|
| id | 可选。规定该元素的唯一的 ID。 |
| xpath | 必需。标识其内容或值用于约束的单个元素或属性。如果该表达式标识一个元素，则该元素必须是简单类型。 |
| xml:lang | 可选。规定内容中使用的语言。 |
Example 1
The following example shows a field element that the "userID" attribute is defined as a field for identifying constraints:
<xs:field xpath="@userID"/>
Complete XML Schema Reference