There are two main ways of representing an absent value in XML. The relevant
element might be omitted entirely, or it might be present with empty
content. (There's a third way, the xsi:nil attribute, but I don't think
anyone uses it.) To answer your question we need to know what the XML looks
like, and what $v1 is.

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: Oleg Konovalov [mailto:olegkon@xxxxxxxxx] 
> Sent: 24 July 2006 20:41
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Comparing to SQL NULL
> 
> Hi,
> 
> I am writing some XSL code processing database columns 
> (actually, adding a new column to the existing table in old 
> application) and need to handle a situation when the column 
> does not have a value yet.
> So how do I express that condition in XSL:
> <xsl:when test="$v1 = 'NULL'">
> ... do something
> </xsl:when>
> or <xsl:when test="$v1 = 'NaN'">
> ... do something
> </xsl:when>
> or <xsl:when test="$v1 = ''">   ... blank string: ''
> ... do something
> </xsl:when>  ???
> 
> Please help.
> 
> Sorry for the newbie question.
> Using XSLT1.0 [and Cocoon 2.0.x]
> 
> Thank you,
> Oleg.