Selecting element from xml using xmlquery in Db2 (SQL/XML) - sql

Question

I have created table in Db2 like this:
create table xml_file(data xml not null)
This is the exact structure of xml:
<?xml version="1.0" encoding="UTF-8" ?>
<student id="20140021">
<name>Tom</name>
<surname>Johnson</surname>
<birth_date>"05/11/1995"</birth_date>
<birth_place>"Miami"</birth_place>
<points>9.45</points>
</student>
I want to select id, name, surname, and points for all students whose names are Ben and birth places are Chicago.
I wrote something like this:
select xmlquery('$DATA/student/data(#id)') as ID,
xmlquery('$DATA/student/name/text()') as NAME,
xmlquery('$DATA/student/surname/text()') as SURNAME,
xmlquery('$DATA/student/points/text()') as POINTS
from xml_file
where xmlexists('$DATA/student[birth_place = "Chicago"]')
and xmlexists('$DATA/student[name = "Ben"]');
All I got is this message: "FETCHED 0 RECORDS, 0 RECORDS SHOWN" (this is in IBM Data Studio).
Can someone tell me what did I do wrong?

Answer 1

Try this:
/*
WITH xml_file (data) AS
(
VALUES
XMLPARSE
(DOCUMENT '<?xml version="1.0" encoding="UTF-8" ?>
<student id="20140021">
<name>Tom</name>
<surname>Johnson</surname>
<birth_date>"05/11/1995"</birth_date>
<birth_place>"Miami"</birth_place>
<points>9.45</points>
</student>'
)
)
*/
SELECT X.*
FROM
xml_file V
, XMLTABLE
('$doc/student' PASSING V.data AS "doc"
COLUMNS
ID INT PATH '#id'
, NAME VARCHAR(20) PATH 'name'
, SURNAME VARCHAR(20) PATH 'surname'
, POINTS DEC(5, 2) PATH 'points'
) X
WHERE XMLEXISTS('$doc/student[birth_place = """Miami""" and name = "Tom"]' PASSING V.data AS "doc");

Answer 2

Try replacing your two where xmlexistss with one (this is used with your sample xml in the question, not your code):
where xmlexists('$DATA//student[birth_place/text()['Miami']][name/text()["Tom"]]');
or, two are required:
where xmlexists('$DATA/student[birth_place/text()['Miami']]')
and xmlexists('$DATA/student[name/text()["Tom"]]');
and see if either works.

Answer 3

The birth-place element contains double quotations marks which lead to an XPath evaluation error. To avoid this, replace where xmlexists('$DATA/student[birth_place = "Chicago"]') with one the following XPath expression :
XPath 1.0 friendly :
where xmlexists('$DATA/student/birth_place[substring(.,2,string-length(/student/birth_place)-2)="Chicago"]')
XPath 2.0 friendly :
where xmlexists('$DATA/student/birth_place[translate(.,codepoints-to-string(34),"")="Chicago"]')
XPath used to test on your sample data :
/student/birth_place[substring(.,2,string-length(/student/birth_place)-2)="Miami"]
/student/birth_place[translate(.,codepoints-to-string(34),"")="Miami"]