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Extract data from a field that looks like XML but the data type is actually nvarchar

Posted on 2016-09-29
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Last Modified: 2016-11-09
Hi there,
We're currently upgrading/migrating a DB where data is polled every hour. The old DB had individual columns (ie. DateTime, Pressure, Temp, etc.), however, for the new one, we found out they captured everything in one column, and formatted as XML.

I tried using SELECT col.value('(/Data/Fields[Name="XXX"]/Value)[1]', 'int'), however after digging around the FieldData column is actually nvarchar, so that didn't work.

I'm trying to figure out how to extract parts of the data within the FieldData column (see highlighted).

Any questions or further info, please let me know...

Much appreciated,
Classic
Output.jpg
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Question by:Classic1
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Accepted Solution

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Barry Cunney earned 500 total points
ID: 41821887
Hi Classic1,
Did you try casting the field as XML?
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Author Comment

by:Classic1
ID: 41822580
Lol...yup, that helped...ok, I was able to cast it as XML, however, when I try to select say Name="000", I get an error (see attached), I made a typo, should be: ('(/Data/Fields/[Name="000"]/Value)[1])
but that didn't do the trick either.

I would like to select the RV's that are highlighted, but I don't know how to create the syntax...first time working with XML.

Much appreciated,
Classic
XML-Output.jpg
XML-Error.jpg
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LVL 17

Assisted Solution

by:Barry Cunney
Barry Cunney earned 500 total points
ID: 41823198
Hi Classic1,
Please try similar to the following:

SELECT
....
....
Field_Data.value('(/Fields/[@Name="000"]/Value)[1]', 'int')

Open in new window


that is to say, prefix 'Name' with @ symbol, as in XML terminology, in your XML output, Name is an attribute
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Author Comment

by:Classic1
ID: 41823738
Hi Barry,
Thanks for the quick response, unfortunately, that didn't work (same error), but I got at little further...and now know the difference between node attributes and elements!
I took out the [] and got a different error. After changing the data type to char(5), it actually ran. It returns a value of 'false', so I don't know what it's actually bringing back...

I've attached some screenshots for reference...

Much appreciated,
Classic1
Error.jpg
Output.jpg
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LVL 17

Assisted Solution

by:Barry Cunney
Barry Cunney earned 500 total points
ID: 41823807
Hi Classic1
Please try

Field_Data.value('(/Data/Fields/Field/@Name="000")[1]', 'char(5)')
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Author Comment

by:Classic1
ID: 41823838
Hi Barry,
Ok, it changed from 'false' to 'true'...

Thanks for the quick responses!
-Classic
Result.jpg
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