How to use AND operator in XPath?

Question

XML is like

 
   value1
   value2
 

I want to write XPath to find id of <

Answer 1

The following XPath,

//a[b = 'value1' and b = 'value2']/@id

will select id attributes of all a elements with a child b element having string value equal to value1 AND another child b element having string value equal to value2 as requested.

Answer 2

contains function can do it.

$nodes = $xpath->query("//b[contains(., 'value1')] | //b[contains(., 'value2')]");

And then, to get the parent id

$parent_id = $nodes->item(0)->parentNode->getAttribute("id");

A demo (with HTML) here.