Processing XML Hierarchy with MS SQL - sql

Question

How would I specify the following XML Hierarchy into readable columns in Microsoft SQL?
<transaction id=1>
<item id=1>
<price>1</price>
</item>
<item id=2>
<price>1</price>
</item>
</transaction>
<transaction>
<item id=1>
<price>1</price>
</item>
</transaction>
for instance
select
x.i.value('(????)','Varchar(max)') [TransId]
x.i.value('(????)','Varchar(max)') [ItemId]
x.i.value('(????)','Varchar(max)') [PriceId]
from #xml.nodes('/transaction') x(i)
Thanks in advance.

Answer 1

Attribute values must always appear in quotation marks in XML.
Not sure about the desired output. An example would be:
declare #xml xml
Select #xml=
'<transaction id="1">
<item id="1">
<price>1</price>
</item>
<item id="2">
<price>2</price>
</item>
</transaction>
<transaction>
<item id="1">
<price>3</price>
</item>
</transaction>'
SELECT
y.value('../#id','int') as TransactionID,
y.value('#id','int') as ItemID,
y.value('(./price/text())[1]', 'Varchar(max)') as Price
FROM #xml.nodes('/transaction/item') as x(y)
order by TransactionID,ItemID
with the output:
NULL 1 3
1 1 1
1 2 2

Answer 2

Actually usually it's faster to shred XML from parent to child using apply, like this:
select
t.c.value('#id','int') as TransId,
i.c.value('#id','int') as ItemId,
i.c.value('(price/text())[1]', 'int') as PriceId
from #xml.nodes('transaction') as t(c)
outer apply t.c.nodes('item') as i(c)
order by TransId, ItemID
sql fiddle demo