XML parsing: line 1, character 345, duplicate attribute - sql-server

Question

I am trying to get the particular attribute value from XML column, but I'm getting an error
XML parsing: line 1, character 345, duplicate attribute
My code:
select
ship_to_cust_num,
tank_num,
tank_capacity_qty,
tank_pkg_type_code,
COALESCE(REPLACE(CAST(CAST(b.tank_inspection AS NTEXT) AS XML).value('(/TankInspection/Questions/Question[#AASAQno="9"]/#QAns)[1]', 'VARCHAR(50)'), '#', ''), 0)
from
bulk_site_tank (nolock)b
where
convert(varchar, b.tank_inspection) != 'NULL'

Answer 1

The simple answer is that the error is telling you the problem. But to explain further. Take this simple statement:
DECLARE #xml varchar(MAX);
SET #XML = '
<root>
<child>
<element attribute="1">value</element>
<element attribute="2" attribute="2">Another Value</element>
</child>
</root>';
SELECT *
FROM (VALUES(CONVERT(xml, #XML)))V(X);
If you run that, you'll get the error:
Msg 9437, Level 16, State 1, Line 11 XML parsing: line 5, character 46, duplicate attribute
Unsurprising, as if you look, the second element node has attribute declared twice.
So, how do you fix this?
Firstly, this means that you're storing your XML data as a datatype other than in an xml data type. XML should be stored using the xml data type (that's exactly what it's for), and only valid XML can be stored in it; as a result you wouldn't have been able to insert invalid XML into the row and wouldn't be in this position. As you are, there's only one thing you can do; find all the "bad" rows:
SELECT tank_inspection
FROM bulk_site_tank
WHERE TRY_CONVERT(xml,tank_inspection) IS NULL
AND tank_inspection IS NOT NULL;
Then inspect every single row returned in the above dataset and fix the data. Make it valid XML. After that, fix your data type:
ALTER TABLE bulk_site_tank ALTER COLUMN tank_inspection xml;
Now everything is valid XML, you can fix that query of yours:
SELECT ship_to_cust_num,
tank_num,
tank_capacity_qty,
tank_pkg_type_code,
REPLACE(b.tank_inspection.value('(/TankInspection/Questions/Question[#AASAQno="9"]/#QAns)[1]', 'varchar(50)'), '#', '') --AS ?
FROM bulk_site_tank b
WHERE b.tank_inspection IS NOT NULL;
Note I change to ANSI_NULL syntax, and got rid of the NOLOCK (as I assume you don't know what it actually does here). The CAST/CONVERT expressions are gone too, and I've removed the COALESCE. As your value expression returns a varchar(50) and the COALESCE has a 0 for the second parameter. This would implicitly cast the value returned from the XML to an int and likely result in a conversion error.
I'm afraid it's up to you to clean up your data though, no one else can help you here I'm afraid. This is just one reason why poor data type choices is a problem; as if the correct data type was used then,as I said before, the invalid XML could never have been inserted.
Good luck!