ASK
Use the ASK query form to determine whether a particular triple pattern exists in the specified data set. ASK returns true or false, depending on whether the solution or match exists.
Syntax
[ PREFIX Clause ] ASK [ FROM Clause ] { triple_template }
Examples
The following example ASK statement queries the sample Tickit data set to ask whether data exists for the event named Wicked:
ASK FROM <http://anzograph.com/tickit> { ?s <http://anzograph.com/tickit/eventname> "Wicked" . }
true