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Hello,</div>
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I have some queries that fail with:</div>
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"ERROR: Period cannot be empty"</div>
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How can I check for this? Is there a 'PERIOD EMPTY' that it could be checked against? Checking for:</div>
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" ... and upper(period(flown_path)) > lower(period(flown_path))"</div>
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does not seem to catch the offending element.</div>
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Thank you.<br>
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