Convert Column XML data to Rows - sql

Question

I am using version PostgreSQL 8.3.12.
Table Column Name : xmltest
id data
Data Column contains XML data that looks like this:
<?xml version="1.0" encoding="utf-8"?>
<ItemData>
<ReviewComments><?xml version="1.0" encoding="utf-8"?>
</ReviewComments>
<SmartTextData RootProtect="True">
<STI_Summary IID="d10c5cbf-f5cf-4478-9f33-4580c1930413" IR="True">
<ObjectValue />
<CP />
<SIProps ST="4" PL="False" PLS="" />
<STI_SummaryActiveProblemsField LIID="cdbd7044-ccde-11db-8cba-df0a56d89593" IID="37742a5f-7998-4715-8d43-0d7a19284d44" IR="True" RW="1">
<HD Title="Active Problems" />
<ObjectValue />
<CP>
<PosReplace />
<NegReplace />
</CP>
<SIProps ST="4" PL="False" PLS="" />
<STI_US>
<ObjectValue>
<TextValue>
<![CDATA[
]]>
</TextValue>
</ObjectValue>
<CP />
<SIProps ST="1" SS=" " PL="False" PLS="" />
</STI_US>
<STI_DxItem LIID="71194038-8ffb-488b-8af5-5f1f1a679115" IID="aaf2de4e-2f1f-409b-87b7-b7265bec37db" RW="1">
<HD Title="Coronary artery disease " />
<ObjectValue>
<Code>
<CodingSystem>ICD-9 CM</CodingSystem>
<Value>414.01</Value>
</Code>
<Code>
<CodingSystem>SWICPC</CodingSystem>
<Value>08.0.K76.CIR</Value>
</Code>
</ObjectValue>
</STI_DxItem >
</STI_Summary>
</SmartTextData>
</ItemData>
I want to spilt XML Tag IID and CODE data to respective ID Column.
Expected Output :
ID LIID Code_Value CodingSystem
1 d10c5cbf-f5cf-4478-9f33-4580c1930413 NULL
1 37742a5f-7998-4715-8d43-0d7a19284d44 NULL
1 aaf2de4e-2f1f-409b-87b7-b7265bec37db 414.01 IC CM
1 aaf2de4e-2f1f-409b-87b7-b7265bec37db 08.0.K76.CIR SWICPC
Note : I am using version PostgreSQL 8.3.12 with this some new syntax of XMLPATH not work.
Simply I want to convert XML Data to rows column structure.
Thanks for Reading this.

Answer 1

Looking at SO questions, I've found this:
ERROR: function unnest(integer[]) does not exist in postgresql
According to the solution of this question, you can implement unnest by your own, on a one-dimension arrays in this way:
CREATE OR REPLACE FUNCTION unnest2(anyarray)
RETURNS SETOF anyelement AS
$BODY$
SELECT $1[i] FROM generate_series(array_lower($1,1), array_upper($1,1)) i;
$BODY$ LANGUAGE sql IMMUTABLE;
This function should allow to query your data using next sentence:
SELECT xpath('/ItemData/SmartTextData/STI_Summary/STI_DxItem/#IID', data, array[array['aaa','example.com']]) as IID,
unnest2(xpath('/ItemData/SmartTextData/STI_Summary/ObjectValue/Code/CodingSystem/text()', data, array[array['aaa','example.com']])) as Code,
unnest2(xpath('/ItemData/SmartTextData/STI_Summary/ObjectValue/Code/Value/text()', data, array[array['aaa','example.com']])) as Value
from xmltest2;
Notice, I've used array[array['aaa','example.com']] as you pointed out in your comments, due your XML data has not schema.
I've tested it in rextester and it works.
+--------------------------------------+----------+--------------+
| iid | code | value |
+--------------------------------------+----------+--------------+
| aaf2de4e-2f1f-409b-87b7-b7265bec37db | ICD-9 CM | 414.01 |
+--------------------------------------+----------+--------------+
| aaf2de4e-2f1f-409b-87b7-b7265bec37db | SWICPC | 08.0.K76.CIR |
+--------------------------------------+----------+--------------+
Check it here: Rextester