What does this xpath function mean?

Asked Jun 13 '18 at 16:49

Active Jun 13 '18 at 16:49

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I'm trying to decode the URL characters such as "&amp" to "&", I found the code works in PostgreSQL - Replace HTML Entities . The code is (xpath('/z/text()', ('<z>' || 'AT&T' || '</z>')::xml))[1] as output.

I try to understand this code and read the document of it, but the only thing I found is the explanation of xpath(xpath, xml [, nsarray]). I'm a freshman on PostgreSQL, and I know the /z/ is like a tag. But what is the "||","1" means? why should it use '/z/text()'.

If there have some links about that, it will very helpful. Thanks a lot.

asked Jun 13 '18 at 16:49

Meilan

|| is string concatenation '' || 'AT&T' || '' is the same as 'AT&T – Stephen Flynn Jun 13 '18 at 16:59
Your code says get the text that is a child of the z element starting at the root of the xml – Stephen Flynn Jun 13 '18 at 17:00

What does this xpath function mean?

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