Loop on XML in SQL Server - sql

Question

I have to query an XML to extract the data and put it into columns. This works perfectly. However, I want to include a loop because the structure in the XML is as follows:
<BlockOrderMessage>
<FlightOrder>
<Flight>
<FlightNr>5</FlightNr>
<AircraftType>A255</AircraftType>
</Flight>
<PositionOrders>
<PositionOrder Unit="Unit 5">
<UnitName>UnitName5</UnitName>
<CardColor>Blue</CardColor>
</PositionOrder>
<PositionOrder Unit='Unit 6">
<UnitName>UnitName6</UnitName>
<CardColor>Red</CardColor>
</PositionOrder>
</PositionOrders>
</FlightOrder>
</BlockOrderMessage>
There's always only one , but there can be more ... Now, I can generate the column (when knowing the amount of ) using following code:
DECLARE #Data XML
SET #Data =
'<?xml version="1.0" encoding="UTF-8"?>
<BlockOrderMessage xmlns="http://www...."
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.... file:/C:/Users/.....xsd">
<FlightOrder>
<Flight>
<FlightNr>FlightNr0</FlightNr>
<AircraftType>AircraftType0</AircraftType>
<PositionOrders>
<PositionOrder Unit="Unit 5">
<UnitName>UnitName5</UnitName>
<CardColor>Blue</CardColor>
</PositionOrder>
<PositionOrder Unit="Unit 6">
<UnitName>UnitName6</UnitName>
<CardColor>Red</CardColor>
</PositionOrder>
</PositionOrders>
</FlightOrder>
</BlockOrderMessage>'
;WITH XMLNAMESPACES (DEFAULT 'http://www....')
SELECT #Data.value('(/BlockOrderMessage/FlightOrder/Flight/FlightNr)[1]','VARCHAR(20)') AS 'FlightNr',
#Data.value('(/BlockOrderMessage/FlightOrder/Flight/AircraftType)[1]','VARCHAR(20)') AS 'AircraftType',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/#Unit)[1]','VARCHAR(30)') AS 'PosOrder1_Unit ',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/UnitName)[1]','VARCHAR(30)') AS 'PosOrder1_UnitName',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/CardColor)[1]','VARCHAR(30)') AS 'PosOrder1_CardColor',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder[2]/#Unit)[1]','VARCHAR(30)') AS 'PosOrder2_Unit',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder[2]/UnitName)[1]','VARCHAR(30)') AS 'PosOrder2_UnitName',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder[2]/CardColor)[1]','VARCHAR(30)') AS 'PosOrder2_CardColor'
But I want to insert a loop for the PositionOrder bit, I tried the following code (only the last part, since the rest stays the same):
;WITH XMLNAMESPACES (DEFAULT 'http://www....')
SELECT #Data.value('(/BlockOrderMessage/FlightOrder/Flight/FlightNr)[1]','VARCHAR(20)') AS 'FlightNr',
#Data.value('(/BlockOrderMessage/FlightOrder/Flight/AircraftType)[1]','VARCHAR(20)') AS 'AircraftType'
DECLARE #counter INT
SET #counter = 1
WHILE (#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/#Unit)[1]') IS NOT NULL)
BEGIN
;WITH XMLNAMESPACES (DEFAULT 'http://www....')
SELECT #Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/#Unit)[1]','VARCHAR(30)') AS 'PosOrder_#counter_Unit ',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/UnitName)[1]','VARCHAR(30)') AS 'PosOrder_#counter_UnitName',
#Data.value('(/BlockOrderMessage/FlightOrder/PositionOrders/PositionOrder/CardColor)[1]','VARCHAR(30)') AS 'PosOrder_#counter_CardColor'
SET #counter = #counter +1
END
GO
Now, I have the following problems with this loop and the result of my query:
The results of the query for the PositionOrder are all NULL, this wasn't the case when I did it without loops.
I get two tables as query result, but I want them in one table. I tried to do it so I only use one SELECT statement, but I can't get the code right.
I want the name of the column to show the counter number: So if we are in the second loop, we want the name of the column to be PosOrder_2_..., now it shows PosOrder_#counter_...
Does anybody know what I am doing wrong or how I should fix this problem?
Thanks in advance!

Answer 1

Are you looking for something like this?
DECLARE #Flights XML = '<BlockOrderMessage>
<FlightOrder>
<Flight>
<FlightNr>5</FlightNr>
<AircraftType>A255</AircraftType>
</Flight>
<PositionOrders>
<PositionOrder Unit="Unit 5">
<UnitName>UnitName5</UnitName>
<CardColor>Blue</CardColor>
</PositionOrder>
<PositionOrder Unit="Unit 6">
<UnitName>UnitName6</UnitName>
<CardColor>Red</CardColor>
</PositionOrder>
</PositionOrders>
</FlightOrder>
</BlockOrderMessage>'
SELECT
FlightNr = FltOrder.value('(Flight/FlightNr)[1]', 'int'),
AircraftType = FltOrder.value('(Flight/AircraftType)[1]', 'varchaR(100)'),
PosOrderUnit = PosOrder.value('#Unit', 'varchar(50)'),
PosOrderUnitName = PosOrder.value('(UnitName)[1]', 'varchar(50)'),
PosOrderCardColor = PosOrder.value('(CardColor)[1]', 'varchar(50)')
FROM
#Flights.nodes('/BlockOrderMessage/FlightOrder') AS XTbl(FltOrder)
CROSS APPLY
FltOrder.nodes('PositionOrders/PositionOrder') AS XTbl2(PosOrder)
This would produce an output something like this:
Basically, it grabs the "base" data from the <BlockOrderMessage> / <FlightOrder> node and displays those in columns 1 & 2, and then it cross applies all subnodes <PositionOrders> / <PositionOrder> inside that <FlightOrder> node and extracts the remaining information from those subnodes (any number of them).