My source data in a SQL Server table has XML structured data. For each of the source rows I need to query the following sample XML structure in a way that I get a calculated value of all A sub elements. For example the `SUM of bb` and product of `cc * dd` over all A elements. 
The number of A elements in the structure is unknown. 

    <root>
    	<A>
    		<bb>bb1</bb>
    		<cc>cc1</cc>
    		<dd>dd1</dd>
    	</A>
    	<A>
    		<bb>bb2</bb>
    		<cc>cc2</cc>
    		<dd>dd2</dd>
    	</A>
    	<A>
    		<bb>bb3</bb>
    		<cc>cc3</cc>
    		<dd>dd3</dd>
    	</A>
    </root>


I experimented with something like this, but it looks like not being the right way:

    SELECT Convert(xml,myXmlCol).value('(/root/A[1]/bb)[1]', 'int') as MyResult FROM SourceTable