Reflexive Schema Validation & Definition - xsd

Question

Can can someone help me on how to define a xsd for this.
I also want enforce validation at schema level such that based on the attribute value given, only the corresponding child tags will be displayed (reflexive based on the attribute value).
<?xml version="1.0" encoding="UTF-8"?>
<root>
<sample-tag type="one">
<one></one>
</sample-tag>
<sample-tag type="two">
<two></two>
</sample-tag>
<sample-tag type="three">
<three></three>
</sample-tag>
<sample-tag type="onetwo">
<one></one>
<two></two>
</sample-tag>
</root>

Answer 1

Not possible with XSD. Check if this is possible with Schematron.

Answer 2

If I take your sample XML as an approximation, then strictly speaking there is one way to achieve the effect you want: it is called xsi:type. I personally dislike xsi:type, so I consider this answer rather an academic exercise.
If you agree with this XML:
<?xml version="1.0" encoding="UTF-8"?>
<root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<sample-tag xsi:type="one">
<one></one>
</sample-tag>
<sample-tag xsi:type="two">
<two></two>
</sample-tag>
<sample-tag xsi:type="three">
<three></three>
</sample-tag>
<sample-tag xsi:type="onetwo">
<one></one>
<two></two>
</sample-tag>
</root>
... then this XSD would give you what you want:
<?xml version="1.0" encoding="utf-8"?>
<!--W3C Schema generated by QTAssistant/W3C Schema Refactoring Module (http://www.paschidev.com)-->
<xsd:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:element name="root">
<xsd:complexType>
<xsd:sequence>
<xsd:element maxOccurs="unbounded" name="sample-tag" type="sample-tag"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:complexType name="sample-tag" abstract="true"/>
<xsd:complexType name="one">
<xsd:complexContent>
<xsd:extension base="sample-tag">
<xsd:sequence>
<xsd:element name="one"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="two">
<xsd:complexContent>
<xsd:extension base="sample-tag">
<xsd:sequence>
<xsd:element name="two"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="three">
<xsd:complexContent>
<xsd:extension base="sample-tag">
<xsd:sequence>
<xsd:element name="three"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="onetwo">
<xsd:complexContent>
<xsd:extension base="sample-tag">
<xsd:sequence>
<xsd:element name="one"/>
<xsd:element name="two"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:schema>
If xsi:type is out of question, and XSD 1.1, then you have to go with #Pangea's answer.