Read multiple lines from xml column to table - sql

Question

I'm struggling reading data from measurements stored as xml columns. My xml files looks like this:
<Data t0="2018-09-18T07:43:11.882+01:00" dt="2.003338853E-5">
<Measurement>
<Value>2.075</Value>
<Value>2.175</Value>
<Value>2.275</Value>
<Value>2.325</Value>
<Value>2.425</Value>
...
</Measurement>
</Data>
What I need as result is a table containing the values.
What I already tried is this:
SELECT CONVERT(varchar(max),c.query('data(Value)')) as XMLValues
FROM [dbo].[T_Measurement] as t1
CROSS APPLY Measurement.nodes('/Data/Measurement') x(c)
which creates a resulting xml field with space separated values. But how can I create a query resulting in a table?
regards, Daniel

Answer 1

You can use query() to extract the values and then value to cast them to a numeric type:
declare #tmp table (Measurement xml)
insert into #tmp
select
'<Data t0="2018-09-18T07:43:11.882+01:00" dt="2.003338853E-5">
<Measurement>
<Value>2.075</Value>
<Value>2.175</Value>
<Value>2.275</Value>
<Value>2.325</Value>
<Value>2.425</Value>
</Measurement>
</Data>'
SELECT
Tbl.Col.value('.','decimal(18,3)') as XMLValues
FROM #tmp as t1
CROSS APPLY Measurement.nodes('/Data/Measurement/Value') Tbl(Col)
Result:
If you have multiple measurements in a single file (for example with an attribute that identifies each Measurement):
DECLARE #tmp TABLE (Measurement XML)
INSERT INTO #tmp
SELECT '<Data t0="2018-09-18T07:43:11.882+01:00" dt="2.003338853E-5">
<Measurement setId="1">
<Value>1.075</Value>
<Value>1.175</Value>
<Value>1.275</Value>
<Value>1.325</Value>
<Value>1.425</Value>
</Measurement>
<Measurement setId="2">
<Value>2.076</Value>
<Value>2.176</Value>
<Value>2.276</Value>
<Value>2.326</Value>
<Value>2.426</Value>
</Measurement>
</Data>'
SELECT
Tbl.Col.value('../#setId', 'int') as setId,
Tbl.Col.value('.', 'decimal(18,3)') as XMLValues
FROM #tmp AS t1
CROSS APPLY Measurement.nodes('/Data/Measurement/Value') Tbl(Col)
Results: