This query lists questions that have been closed as duplicates of another question that has since been deleted. Such questions should be either deleted or, if they have good answers or are otherwise of decent quality, reopened. Note that non-locked questions with no answers and a negative score will be automatically deleted by the RemoveDeadQuestions script after 30 days, as indicated by the "Roombable?" column.
By default, the results will be sorted with the most recently closed questions first. You can click the column headings to change the sort order. For example, questions with a high answer score may be good candidates for reopening (or for a historical lock), while questions with a high score but no answers may simply need a new dupe target (see http://meta.stackexchange.com/q/291824).
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SELECT TOP 50 PostId as [Post Link] FROM PostLinks
WHERE LinkTypeId = 3