Yes, it is possible: on the element declaration for the parent of the Hardware element, use something like
<xs:unique name="u">
<xs:selector xpath="Hardware"/>
<xs:field xpath="COMPort"/>
<xs:field xpath="BaudRate"/>
</xs:unique>
문제
Is it possible to validate through schema if combination of element values is unique?
Valid:
<Hardware ID="1">
<COMPort>COM1</COMPort>
<BaudRate>9600</BaudRate>
</Hardware>
<Hardware ID="2">
<COMPort>COM2</COMPort>
<BaudRate>9600</BaudRate>
</Hardware>
<Hardware ID="3">
<COMPort>COM1</COMPort>
<BaudRate>115200</BaudRate>
</Hardware>
Invalid:
<Hardware ID="1">
<COMPort>COM1</COMPort>
<BaudRate>9600</BaudRate>
</Hardware>
<Hardware ID="2">
<COMPort>COM2</COMPort>
<BaudRate>9600</BaudRate>
</Hardware>
<Hardware ID="3">
<COMPort>COM1</COMPort>
<BaudRate>9600</BaudRate>
</Hardware>
This code is invalid because the combination of comport and baudrate is not unique.
해결책
Yes, it is possible: on the element declaration for the parent of the Hardware element, use something like
<xs:unique name="u">
<xs:selector xpath="Hardware"/>
<xs:field xpath="COMPort"/>
<xs:field xpath="BaudRate"/>
</xs:unique>