flattening xml data in sql server - sql-server

Question

I have the following xml data in a xml column (not typed) called xml_response
<SEIContent>
<Request>
<eq:Charge>
<v:Type>MaintCharge</v:Type>
<v:Term>0</v:Term>
<v:StartMonth>0</v:StartMonth>
<v:EndMonth>0</v:EndMonth>
<v:Rate>0</v:Rate>
<v:RebateRatio>0</v:RebateRatio>
<v:MaxRebate>0</v:MaxRebate>
<v:TieredCharge>
<v:Term>0</v:Term>
<v:Rate>0.75</v:Rate>
<v:LowerBand>0</v:LowerBand>
<v:UpperBand>249999.99</v:UpperBand>
<v:BandCurrency>GBP</v:BandCurrency>
</v:TieredCharge>
<v:TieredCharge>
<v:Term>0</v:Term>
<v:Rate>0.7</v:Rate>
<v:LowerBand>250000</v:LowerBand>
<v:UpperBand>499999.99</v:UpperBand>
<v:BandCurrency>GBP</v:BandCurrency>
</v:TieredCharge>
<v:TieredCharge>
<v:Term>0</v:Term>
<v:Rate>0.6</v:Rate>
<v:LowerBand>500000</v:LowerBand>
<v:UpperBand>999999.99</v:UpperBand>
<v:BandCurrency>GBP</v:BandCurrency>
</v:TieredCharge>
<v:TieredCharge>
<v:Term>0</v:Term>
<v:Rate>0.5</v:Rate>
<v:LowerBand>1000000</v:LowerBand>
<v:UpperBand>9999999.99</v:UpperBand>
<v:BandCurrency>GBP</v:BandCurrency>
</v:TieredCharge>
</eq:Charge>
<eq:Charge>
<v:Type>MaintCharge</v:Type>
<v:Term>0</v:Term>
<v:StartMonth>0</v:StartMonth>
<v:EndMonth>59</v:EndMonth>
<v:Rate>1.5</v:Rate>
<v:RebateRatio>0</v:RebateRatio>
<v:MaxRebate>0</v:MaxRebate>
</eq:Charge>
<eq:Charge>
<v:Type>MaintCharge</v:Type>
<v:Term>0</v:Term>
<v:StartMonth>60</v:StartMonth>
<v:EndMonth>0</v:EndMonth>
<v:Rate>0.5</v:Rate>
<v:RebateRatio>0</v:RebateRatio>
<v:MaxRebate>0</v:MaxRebate>
</eq:Charge>
<eq:Charge>
<v:Type>QAC</v:Type>
<v:Basis>FixedAmount</v:Basis>
<v:Term>0</v:Term>
<v:StartMonth>0</v:StartMonth>
<v:EndMonth>0</v:EndMonth>
<v:Rate>105</v:Rate>
<v:RebateRatio>0</v:RebateRatio>
<v:MaxRebate>0</v:MaxRebate>
</eq:Charge>
</Request>
<Response>
<eq:Ref>QV00000393</eq:Ref>
</Response>
</SEIContent>
So you'll notice that some charges contain a repeating element TieredCharge and some don't
I've written the following query:
WITH XMLNAMESPACES('http://lu/blah' AS eq, 'http://lu/blah2' AS v,
DEFAULT 'http://lu/blah3'
SELECT
nref.value('Response[1]/eqRef[1]', 'nvarchar(200)') Ref,
ncharge.value('v:Type[1]', 'nvarchar(50)') ChargeType,
ncharge.value('v:Basis[1]', 'nvarchar(50)') ChargeBasis,
ncharge.value('v:Term[1]', 'int') Term,
ncharge.value('v:StartMonth[1]', 'int') StartMonth,
ncharge.value('v:EndMonth[1]', 'int') EndMonth,
ncharge.value('v:Rate[1]', 'money') Rate,
ncharge.value('v:RebateRatio[1]', 'money') RebateRatio,
ncharge.value('v:MaxRebate[1]', 'money') MaxRebate,
tcharge.value('v:Term[1]', 'int') TieredTerm,
tcharge.value('v:Rate[1]', 'money') TieredRate,
tcharge.value('v:LowerBand[1]', 'money') TieredLowerBand,
tcharge.value('v:UpperBand[1]', 'money') TieredUpperBand
INTO #TempCharges
FROM xml_response CROSS APPLY response_body.nodes('//SEIContent') AS Quote(nref)
CROSS APPLY response_body.nodes('//Request//eq:Charge') AS Charge(ncharge)
CROSS APPLY response_body.nodes('//Request//eq:Charge//v:TieredCharge') AS TieredCharge(tcharge)
WHERE nref.value('Request[1]/eq:Product[1]', 'nvarchar(60)') <> 'AVL'
select * from #TempCharges
So although this flattens the xml, what I'm getting is repeated rows even if the eq:Charge element doesn't contain a v:TieredCharge repeating element?
For example I get 4 rows where the charge type is QAC even though there is only one element with that type?
How do I query this so that I only get one row for each Charge element, unless there are repeating child elements below it, in which case I'll only get the rows repeated for each element?
So I should get something like this:
MaintChange TieredCharge1 row
MaintChange TieredCharge2 row
MaintChange TieredCharge3 row
MaintChange TieredCharge4 row
MaintCharge
MaintCharge
QAC

Answer 1

So the trick is to use OUTER APPLY in the last bit of the query - its kind of like an inner join. Then it works.