How to use XPATH in MySQL select?

Question

Say I have a table called "xml" that stores XML files in a single column "data". How would I write a MySQL query that run an XPath and return only rows matching that XPath?

Answer 1

I just got the answer from a colleague, it seems trimming the xml often helps:

select * from xml where 
   trim(both '\r\n' from ExtractValue(xml, '/some/xpath')) = 'value';

Answer 2

SELECT * FROM xml
WHERE EXTRACTVALUE(data, '<xpath-expr>') != '';

You should note, however, that there are limitations to MySQL's support of XPath.

• EXTRACTVALUE() returns only CDATA.
• Not all XPath constructions are supported. Details under the heading "XPath limitations" on the doc page mentioned in abatishchev's answer.