How to get a value from Specific XML Node

Question

Hi all,
I'm just trying to introduce to XMLType and see the potencialities of that.
DB version:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi
PL/SQL Release 10.2.0.5.0 - Production
CORE     10.2.0.5.0     Production
TNS for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Productio
NLSRTL Version 10.2.0.5.0 - Production
I'm a table with just one CLOB field:
CREATE TABLE asm_test
(doc XMLType NOT NULL)
XMLTYPE doc STORE AS CLOB;
Then i've inserted the following XML data:
<?xml version="1.0" encoding="UTF-8" ?>
- <ReceiptDesc>
<appt_nbr>2142473</appt_nbr>
- <Receipt>
<dc_dest_id>401</dc_dest_id>
<po_nbr>2142473</po_nbr>
<document_type>P</document_type>
<asn_nbr />
- <ReceiptDtl>
<item_id>509720</item_id>
<unit_qty>83.0000</unit_qty>
<receipt_xactn_type>R</receipt_xactn_type>
+ <receipt_date>
<year>2012</year>
<month>09</month>
<day>17</day>
<hour>15</hour>
<minute>33</minute>
<second>49</second>
</receipt_date>
<receipt_nbr>6902340</receipt_nbr>
<container_id>1</container_id>
<to_disposition>ATS</to_disposition>
<user_id>NTCPO01</user_id>
<catch_weight />
</ReceiptDtl>
- <ReceiptDtl>
<item_id>509740</item_id>
<unit_qty>17.0000</unit_qty>
<receipt_xactn_type>R</receipt_xactn_type>
+ <receipt_date>
<year>2012</year>
<month>09</month>
<day>17</day>
<hour>15</hour>
<minute>33</minute>
<second>49</second>
</receipt_date>
<receipt_nbr>6902344</receipt_nbr>
<container_id>1</container_id>
<to_disposition>ATS</to_disposition>
<user_id>NTCPO01</user_id>
<catch_weight />
</ReceiptDtl>
</Receipt>
</ReceiptDesc>
And then i have started to make some tests to retrieve data from.
SELECT EXTRACTVALUE(doc, '/ReceiptDesc/appt_nbr') FROM asm_test; -- got the correct value 2142473
SELECT EXTRACTVALUE(doc, '/ReceiptDesc/Receipt/dc_dest_id') FROM asm_test; ---- got the correct value 401
select count(*) from asm_jam_test d where (d.doc.getClobVal()) like '%NTCPO01%'; -- got 1
But i need to find a Specific data from XML (the main goal is to update a value inside XML).
If i try this:
select extract(doc, '/ReceiptDesc/Receipt/ReceiptDtl/item_id/text()').getstringVal() from asm_test                     
where existsNode(doc,'/ReceiptDesc/Receipt/ReceiptDtl/receipt_nbr') = 1;
got: 509720509740 -- which are the concatenate of 2 Item_ids
when i try to find out the Item_id of specific receipt_nbr i got a NULL response.
select extract(doc, '/ReceiptDesc/Receipt/ReceiptDtl/item_id/text()').getstringVal()
from  asm_test                     
where existsNode(doc,'/ReceiptDesc/Receipt/ReceiptDtl/receipt_nbr') = 1 and
extract(doc,'/ReceiptDesc/Receipt/ReceiptDtl/receipt_nbr/text()').getstringVal() = '6902340';
What i'm doing wrong or which is the best way to get data from XML?
Many thanks in advance

Answer 1

Hi,
Thanks for providing db version and sample data in the first place.
Don't forget to use the &#x7B;code} tags to preserve formatting.
Also, when posting XML, do not copy/paste directly from your browser as it retains +/- signs and therefore needs extra processing on our side.
select count(*) from asm_jam_test d where (d.doc.getClobVal()) like '%NTCPO01%'; -- got 1No, don't do it like that.
Use existsNode() function in this situation :
SQL> select count(*)
  2  from asm_test
  3  where existsNode(doc, '/ReceiptDesc/Receipt/ReceiptDtl[user_id="NTCPO01"]') = 1
  4  ;
  COUNT(*)
         1
when i try to find out the Item_id of specific receipt_nbr i got a NULL response.Yes, that's because this :
extract(doc,'/ReceiptDesc/Receipt/ReceiptDtl/receipt_nbr/text()').getstringVal()returns :
69023406902344So obviously it cannot be equal to '6902340'.
When you have to deal with repeating nodes individually, use XMLTable function to break the structure into relational rows and columns.
The resultset you'll get acts as a virtual table (or inline view) you can then manipulate with SQL operations :
SQL> select x.*
  2  from asm_test t
  3     , xmltable(
  4         '/ReceiptDesc/Receipt/ReceiptDtl'
  5         passing t.doc
  6         columns item_id     varchar2(15) path 'item_id'
  7               , receipt_nbr varchar2(15) path 'receipt_nbr'
  8       ) x
  9  ;
ITEM_ID         RECEIPT_NBR
509720          6902340
509740          6902344
Now, you can just add a WHERE clause to filter the RECEIPT_NBR you require :
SQL> select x.item_id
  2  from asm_test t
  3     , xmltable(
  4         '/ReceiptDesc/Receipt/ReceiptDtl'
  5         passing t.doc
  6         columns item_id     varchar2(15) path 'item_id'
  7               , receipt_nbr varchar2(15) path 'receipt_nbr'
  8       ) x
  9  where x.receipt_nbr = '6902340'
10  ;
ITEM_ID
509720
That can also be achieved with EXTRACTVALUE and a single XPath expression (assuming RECEIPT_NBR is unique) :
SQL> select extractvalue(
  2           doc
  3         , '/ReceiptDesc/Receipt/ReceiptDtl[receipt_nbr="6902340"]/item_id'
  4         ) as item_id
  5  from asm_test
  6  ;
ITEM_ID
509720