[Tracker] Editing a tag: SPARQL help wanted

[Debarshi Ray <debarshi ray gmail com>]

In Solang, the nao:Tags are sometimes nie:InformationElements too to
allow the user to add some textual comment or description to the tags
in addition to the nao:prefLabel, which is more like the name of the
tag.

Right now we are using the following piece of SPARQL to edit these
tags, which is broken because tags are not always
nie:InformationElements.

DELETE {
  <urn:XXX:ZZZ> nao:prefLabel 'Old Label' ;
  nie:comment 'Old Comment' .
}
INSERT {
  <urn:XXX:ZZZ> nao:prefLabel 'New Label' ;
  nie:comment 'New Label' .
}

What is the best way to do this?

Thanks,
Debarshi
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