所以我在这里有一个XML模式：
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified">
<xs:element name="couriersystem">
<xs:complexType>
<xs:sequence>
<!-- branches -->
<xs:element name="branches">
<xs:complexType>
<xs:sequence>
<xs:element name="branch" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="name" type="xs:string" />
<xs:element name="address" type="xs:string" />
<!-- foreign key to employee (manager) -->
<xs:element name="manager">
<xs:complexType>
<xs:attribute name="mid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
<!-- foreign key to branch (head office) -->
<xs:element name="headoffice">
<xs:complexType>
<xs:attribute name="hid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
<!-- delivery methods -->
<xs:element name="deliverymethods">
<xs:complexType>
<xs:sequence>
<xs:element name="method" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="name" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="bid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- employees -->
<xs:element name="employees">
<xs:complexType>
<xs:sequence>
<xs:element name="employee" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="nin">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[A-CEGHJ-PR-TW-Z]{1}[A-CEGHJ-NPR-TW-Z]{1}[0-9]{6}[A-DFM]{0,1}" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="firstname" type="xs:string" />
<xs:element name="lastname" type="xs:string" />
<xs:element name="gender">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="Male|Female" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="dob" type="xs:date" />
<xs:element name="email">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[^@]+@[^\.]+\..+" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="address" type="xs:string" />
<xs:element name="tel">
<xs:simpleType>
<xs:restriction base="xs:string">
<!--
Accepts the following:
07222 555555 | (07222) 555555 | +44 7222 555 555
-->
<xs:pattern value="(07\d{8,12}|447\d{7,11})" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="salary" type="xs:positiveInteger" />
<!-- foreign key to branch (employee's branch) -->
<xs:element name="empbranch">
<xs:complexType>
<xs:attribute name="bid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
<!-- foreign key to employee (supervisor) -->
<xs:element name="supervisor">
<xs:complexType>
<xs:attribute name="sid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="eid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
<!-- key reference to employee ID for use as a foreign key -->
<xs:key name="employeeID">
<xs:selector xpath="employee" />
<xs:field xpath="@eid" />
</xs:key>
</xs:element>
<!-- customers -->
<xs:element name="customers">
<xs:complexType>
<xs:sequence>
<xs:element name="customer" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="firstname" type="xs:string" />
<xs:element name="lastname" type="xs:string" />
<xs:element name="gender">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="Male|Female" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="dob" type="xs:date" />
<xs:element name="email">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:pattern value="[^@]+@[^\.]+\..+" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="address" type="xs:string" />
<xs:element name="tel">
<xs:simpleType>
<xs:restriction base="xs:string">
<!--
Accepts the following:
07222 555555 | (07222) 555555 | +44 7222 555 555
-->
<xs:pattern value="(07\d{8,12}|447\d{7,11})" />
</xs:restriction>
</xs:simpleType>
</xs:element>
<!-- foreign key to branch (customer's branch id) -->
<xs:element name="cbranch">
<xs:complexType>
<xs:attribute name="bid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="cid" type="xs:positiveInteger" use="required" />
</xs:complexType>
<!-- key reference to employee ID for use as a foreign key -->
<xs:key name="customerID">
<xs:selector xpath="customer" />
<xs:field xpath="@cid" />
</xs:key>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- packages -->
<xs:element name="packages">
<xs:complexType>
<xs:sequence>
<xs:element name="package" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="name" type="xs:string" />
<xs:element name="weight" type="xs:decimal" />
<xs:element name="price" type="xs:positiveInteger" />
<xs:element name="category" type="xs:string" />
</xs:sequence>
<xs:attribute name="pid" type="xs:positiveInteger" use="required" />
<!-- link to customer id -->
<xs:attribute name="cid" type="xs:positiveInteger" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="title" type="xs:string" use="required" />
</xs:complexType>
<xs:keyref refer="employeeID" name="FK_managerID">
<xs:selector xpath="branches/branch/manager" />
<xs:field xpath="@mid" />
</xs:keyref>
<xs:keyref refer="employeeID" name="FK_supervisorID">
<xs:selector xpath="employees/employee/supervisor" />
<xs:field xpath="@sid" />
</xs:keyref>
<xs:keyref refer="customerID" name="FK_customerIDForPackage">
<xs:selector xpath="packages/package" />
<xs:field xpath="@cid" />
</xs:keyref>
</xs:element>
</xs:schema>
现在，密钥如下： - 员工ID - customerID
应该清楚这些应该在哪里引导，即employeeID是分支的managerID以及员工的supervisorID。
但它没有用！
这是我的文件：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xml-stylesheet type="text/xsl" href="couriersystem.xsl"?>
<couriersystem title="Courier System"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="couriersystem.xsd">
<branches>
<branch bid="1">
<name>Headquarters</name>
<address>
58, Main Street, Edinburgh, R79 2LR
</address>
<manager mid="1" />
<headoffice hid="1" />
<!-- delivery methods -->
<deliverymethods>
<method name="none" />
</deliverymethods>
</branch>
</branches>
<employees>
<employee eid="1">
<nin>AZ123518D</nin>
<firstname>Peter</firstname>
<lastname>Smith</lastname>
<gender>Male</gender>
<dob>1994-02-11</dob>
<email>ps11@gmail.com</email>
<address>
119, London Street, Nidrie, F57 8NE
</address>
<tel>07005748900</tel>
<salary>30526</salary>
<empbranch bid="1" />
<supervisor sid="1" />
</employee>
</employees>
<customers>
<customer cid="1">
<firstname>Sam</firstname>
<lastname>Mitchell</lastname>
<gender>Male</gender>
<dob>1991-12-12</dob>
<email>sammitch@hotmail.co.uk</email>
<address>
161, South Road, Nidrie, W79 8WG
</address>
<tel>07811119542</tel>
<cbranch bid="1" />
</customer>
</customers>
<packages>
<package pid="1" cid="1">
<name>ACER Aspire F5-571 Laptop</name>
<weight>3.5</weight>
<price>30</price>
<category></category>
</package>
</packages>
</couriersystem>
答案 0 :(得分：1)
customerID密钥应在customers元素中声明（不在customer元素中）。
<xs:element name="customers">
<xs:complexType>
...
</xs:complexType>
<!-- key reference to employee ID for use as a foreign key -->
<xs:key name="customerID">
<xs:selector xpath="customer" />
<xs:field xpath="@cid" />
</xs:key>
</xs:element>