Getting XML out of a table created in SQL - sql

Question

I have created this table in Oracle SQL Developer
CREATE TABLE Test_T (
COL_1 VARCHAR(30),
COL_2 XMLTYPE
);
And have inserted this into it
INSERT INTO Test_T VALUES ('two', ('<?xml version="1.0" encoding="UTF-8"?>
<CATALOG>
<PLANT>
<COMMON>Bloodroot</COMMON>
<BOTANICAL>Sanguinaria canadensis</BOTANICAL>
<ZONE>4</ZONE>
<LIGHT>Mostly Shady</LIGHT>
<PRICE>$2.44</PRICE>
<AVAILABILITY>031599</AVAILABILITY>
</PLANT>
<PLANT>
<COMMON>Columbine</COMMON>
<BOTANICAL>Aquilegia canadensis</BOTANICAL>
<ZONE>3</ZONE>
<LIGHT>Mostly Shady</LIGHT>
<PRICE>$9.37</PRICE>
<AVAILABILITY>030699</AVAILABILITY>
</PLANT></CATALOG>'));
My goal is to return the <COMMON> Name </COMMON> ONLY WHERE the zone is 3 or LESS. So this should return Columbine.
I thought about using XMLExists Im not too familiar with XML so this is what I had so far.
SELECT COL_2 FROM Test_T WHERE XMLExists('//ZONE[COL_2 <= 3]' PASSING BY REF COL_2);
I'm not sure if I am accessing the ZONE right.
Could anyone guide me in the right direction?

Answer 1

Try the below select query :
SELECT COMMON_NAME FROM Test_T WHERE XMLExists( 'CATALOG/PLANT[ZONE<=3]/COMMON[text()]' PASSING COMMON_NAME )

Answer 2

The problem is with your path( '//ZONE[COL_2 <= 3]' ). COL_2 is not a valid XML node, it's just the name of your column.
The proper path would be //ZONE[text() <= 3].
text() is a special node reference that tells oracle to grab the text inside the ZONE node <ZONE>THIS TEXT</ZONE>. You can only target nodes in your actual XML schema.
Also, be aware that the path is CASE SENSITIVE to what's in your XML. Remembering that will save you time.
Additionally, another way to write your select would be this. In this example, Oracle does an implicit join and returns a row for each //PLANT with /ZONE/text() <= 3. The path in the XMLSEQUENCE is important here because it determines how oracle splits up each row, meaning that you can't just target //ZONE because you would only get a row for each ZONE rather than a row for each PLANT.
In the select clause, you can extract individual node values for each PLANT if you have more than one.
SELECT VALUE(P) --THE FULL XML FOR EACH PLANT
VALUE(P).EXTRACT('//COMMON/text()').getstringval() AS COMMON, --INDIVIDUAL NODE VALUE
VALUE(P).EXTRACT('//BOTANICAL/text()').getstringval() AS BOTANICAL --INDIVIDUAL NODE VALUE
FROM Test_T, TABLE(XMLSEQUENCE(EXTRACT(COL_2, '//PLANT[ZONE<= 3]'))) p