XML Functions • lang() •The following XPath functions are not supported, or have known issues as indicated: • id() • local-name() • name() • namespace-uri() • normalize-space() • starts-with() • string() • substring-after() • substring-before() • translate() •The following axes are not supported: • following-sibling • following • preceding-sibling • preceding XPath expressions passed as arguments to  ExtractValue()  and  UpdateXML()  may contain the colon character ( : ) in element selectors, which enables their use with markup employing XML namespaces notation. For example: This is similar in some respects to what is permitted by Apache Xalan and some other parsers, and is much simpler than requiring namespace declarations or the use of the  namespace-uri()  and  local- name()  functions. mysql>  SET @xml = ’<a>111<b:c>222<d>333</d><e:f>444</e:f></b:c></a>’; Query OK, 0 rows affected (0.00 sec) mysql>  SELECT ExtractValue(@xml, ’//e:f’); +-----------------------------+ | ExtractValue(@xml, ’//e:f’) | +-----------------------------+ | 444 | +-----------------------------+ 1 row in set (0.00 sec) mysql>  SELECT UpdateXML(@xml, ’//b:c’, ’<g:h>555</g:h>’); +--------------------------------------------+ | UpdateXML(@xml, ’//b:c’, ’<g:h>555</g:h>’) | +--------------------------------------------+ | <a>111<g:h>555</g:h></a> | +--------------------------------------------+ 1 row in set (0.00 sec) 2255