xml架构中的主键和外键

Question

我试图在下面的XSD架构文件中插入主键和外键: -

主键是StudentID,外键是courseID,AddressID,GradeID.

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="Student">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Title" type="xs:string"/>
      <xs:element name="FirstName" type="xs:string"/>
      <xs:element name="LastName" type="xs:string"/>
      <xs:element name="Dateborn"  type="xs:date"/>
      <xs:element name="Gender"  type="xs:string"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>
</xs:schema>

但是上面的代码在我的设置中不起作用请帮我跟踪问题,

Answer 1

一般来说,您需要在问题中添加更多细节...所以这应该足以了解您可能需要定义的其他内容以及如何定义.我将通过说明假定的学生/地址关系来解决了解如何定义主键/外键所需的内容.

首先,您需要定义这些约束适用的上下文.在我修改过的XSD中,我称之为"世界".

<?xml version="1.0" encoding="utf-8" ?>
<!-- XML Schema generated by QTAssistant/XSD Module (http://www.paschidev.com) -->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="World">
        <xs:complexType>
            <xs:sequence>
                <xs:element ref="Student" maxOccurs="unbounded"/>   
                <xs:element ref="Address" minOccurs="0" maxOccurs="unbounded"/>
            </xs:sequence>          
        </xs:complexType>
        <xs:key name="PKStudents">
            <xs:selector xpath="Student/StudentID"/>
            <xs:field xpath="."/>
        </xs:key>
        <xs:key name="PKAddresses">
            <xs:selector xpath="Address/AddressID"/>
            <xs:field xpath="."/>
        </xs:key>
        <xs:keyref name="FKStudentToAddress" refer="PKAddresses">
            <xs:selector xpath="Student/AddressID"/>
            <xs:field xpath="."/>
        </xs:keyref>
    </xs:element>
    <xs:element name="Student">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="Title" type="xs:string"/>
                <xs:element name="FirstName" type="xs:string"/>
                <xs:element name="LastName" type="xs:string"/>
                <xs:element name="Dateborn" type="xs:date"/>
                <xs:element name="Gender" type="xs:string"/>
                <xs:element name="StudentID" type="xs:string"/>
                <xs:element name="AddressID" type="xs:string" minOccurs="0"/>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
    <xs:element name="Address">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="AddressID" type="xs:string"/>
                <xs:element name="Street" type="xs:string"/>
                <xs:element name="City" type="xs:string"/>
                <xs:element name="Province" type="xs:string" minOccurs="0"/>
                <xs:element name="Country" type="xs:date" minOccurs="0"/>
                <xs:element name="PostalCode" type="xs:string" minOccurs="0"/>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
</xs:schema>

那么像这样的XML会通过或失败,具体取决于您对StudentID和AddressID字段中的值的处理方式.

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<!-- Sample XML generated by QTAssistant (http://www.paschidev.com) -->
<World xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <Student>
        <Title>Title1</Title>
        <FirstName>FirstName1</FirstName>
        <LastName>LastName1</LastName>
        <Dateborn>1900-01-01</Dateborn>
        <Gender>Gender1</Gender>
        <StudentID>StudentID1</StudentID>
        <AddressID>AddressID1</AddressID>
    </Student>
    <Student>
        <Title>Title1</Title>
        <FirstName>FirstName1</FirstName>
        <LastName>LastName1</LastName>
        <Dateborn>1900-01-01</Dateborn>
        <Gender>Gender1</Gender>
        <StudentID>StudentID2</StudentID>
        <AddressID>AddressID1</AddressID>
    </Student>
    <Address>
        <AddressID>AddressID1</AddressID>
        <Street>Street1</Street>
        <City>City1</City>
        <Province>Province1</Province>
        <Country>1900-01-01</Country>
        <PostalCode>PostalCode1</PostalCode>
    </Address>
    <Address>
        <AddressID>AddressID2</AddressID>
        <Street>Street1</Street>
        <City>City1</City>
        <Province>Province1</Province>
        <Country>1900-01-01</Country>
        <PostalCode>PostalCode1</PostalCode>
    </Address>
</World>

要完成解决方案,您需要在"世界"中定义课程和成绩 "实体",xs:key为每个实体定义,类似于学生/*地址*,然后将CourseID和GradeID属性添加到需要它们的实体,以及最后,定义keyref,如上述,对于实体到级和实体到课程.