forcing attribute in XSD Schema to be the primary key ( and sorted)

Question

In the XML shown below, Is there a way to create a schema that will describe the XML so that the id value will increase by 1 with the addition of each Book node. The goal is to use id as a primary key whose minimum value = 1. Also, id values should be are sorted in an ascending manner.

<Books>
    <Book id="1"></Book>
    <Book id="2"></Book>
    <Book id="3"></Book>
    <Book id="4"></Book>
    ...
</Books>

Answer 1

No. you cannot do that in xsd.

xsd defines the xml schema not the xml data. you will need to do that in your code that parses the xml data.

Answer 2

I think the closest you can get is this:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
    <xs:element name="Books">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="Book">
                    <xs:complexType>
                        <xs:attribute name="id" type="id_type" />
                    </xs:complexType>
                </xs:element>
            </xs:sequence>
        </xs:complexType>
        <xs:key name="PK_BookID">
            <xs:selector xpath="Books/Book" />
            <xs:field xpath="@id" />
        </xs:key>
        <xs:unique name="BookIdUnique">
            <xs:selector xpath="Books/Book" />
            <xs:field xpath="@id" />
        </xs:unique>
    </xs:element>
    <xs:simpleType name="id_type">
        <xs:restriction base="xs:integer">
            <xs:minInclusive value="1" />
        </xs:restriction>
    </xs:simpleType>
</xs:schema>

I cannot think of any way to enforce sorting and an id sequence without gaps but as this.__curious_geek already stated XSD is not meant for this.