说明:

xmlns="http://www.w3.org/2001/XMLSchema"：

默认命名空间(包名),当引用这个空间下的元素时，可以不加前缀,如schema,element,complexType

targetNamespace="http://www.nl.org/mapper":

本文档的命令空间

xmlns:tns="http://www.nl.org/mapper"

引用本文档的元素时，需要加前缀:tns,如tns:if

mapper.xsd

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" 
		targetNamespace="http://www.nl.org/mapper"
		xmlns:tns="http://www.nl.org/mapper"
		elementFormDefault="qualified">
	<element name="mapper">
		<complexType>
			<sequence maxOccurs="unbounded" minOccurs="0" >
				<choice>
					<element name="insert" >
						<complexType mixed="true">
							<choice>
								<sequence minOccurs="0" maxOccurs="unbounded">
									<element name="if" type="tns:if">
									</element>
								</sequence>
							</choice>
							<attribute name="id" type="string" use="required"></attribute>
						</complexType>
					</element>
					<element name="delete" >
						<complexType mixed="true">
							<choice>
								<sequence minOccurs="0" maxOccurs="unbounded">
									<element name="if" type="tns:if">
									</element>
								</sequence>
							</choice>
							<attribute name="id" type="string" use="required"></attribute>
						</complexType>
					</element>
					<element name="update" >
						<complexType mixed="true">
							<choice>
								<sequence minOccurs="0" maxOccurs="unbounded">
									<element name="if" type="tns:if">
									</element>
								</sequence>
							</choice>
							<attribute name="id" type="string" use="required"></attribute>
						</complexType>
					</element>
					<element name="select" >
						<complexType mixed="true">
							<choice>
								<sequence minOccurs="0" maxOccurs="unbounded">
									<element name="if" type="tns:if">
									</element>
								</sequence>
							</choice>
							<attribute name="id" type="string" use="required"></attribute>
						</complexType>
					</element>
				</choice>
			</sequence>
			<attribute name="namespace" type="string" use="required"></attribute>
		</complexType>
	</element>
	
	<complexType name="if" mixed="true">
		<attributeGroup ref="tns:if_group"></attributeGroup>
	</complexType>
	<attributeGroup name="if_group">
		<attribute name="property" type="string" use="required"></attribute>
		<attribute name="notNull" type="string" use="optional"></attribute>
		<attribute name="equals" type="string" use="optional"></attribute>
		<attribute name="noEquals" type="string" use="optional"></attribute>
	</attributeGroup>
</schema>