CREATE TABLE PostTags (PostId NUMBER, TagId NUMBER)
CREATE TABLE CloseReasonTypes (Id NUMBER, Name CLOB, Description CLOB)
CREATE TABLE ReviewTaskStates (Id NUMBER, Name CLOB, Description CLOB)
CREATE TABLE CloseAsOffTopicReasonTypes (Id NUMBER, IsUniversal BOOLEAN, InputTitle CLOB, MarkdownInputGuidance CLOB, MarkdownPostOwnerGuidance CLOB, MarkdownPrivilegedUserGuidance CLOB, MarkdownConcensusDescription CLOB, CreationDate TIME, CreationModeratorId NUMBER, ApprovalDate TIME, ApprovalModeratorId NUMBER, DeactivationDate TIME, DeactivationModeratorId NUMBER)
CREATE TABLE TagSynonyms (Id NUMBER, SourceTagName CLOB, TargetTagName CLOB, CreationDate TIME, OwnerUserId NUMBER, AutoRenameCount NUMBER, LastAutoRename TIME, Score NUMBER, ApprovedByUserId NUMBER, ApprovalDate TIME)
CREATE TABLE Posts (Id NUMBER, PostTypeId NUMBER, AcceptedAnswerId NUMBER, ParentId NUMBER, CreationDate TIME, DeletionDate TIME, Score NUMBER, ViewCount NUMBER, Body CLOB, OwnerUserId NUMBER, OwnerDisplayName CLOB, LastEditorUserId NUMBER, LastEditorDisplayName CLOB, LastEditDate TIME, LastActivityDate TIME, Title CLOB, Tags CLOB, AnswerCount NUMBER, CommentCount NUMBER, FavoriteCount NUMBER, ClosedDate TIME, CommunityOwnedDate TIME, ContentLicense CLOB)
CREATE TABLE ReviewTaskTypes (Id NUMBER, Name CLOB, Description CLOB)
CREATE TABLE ReviewTaskResults (Id NUMBER, ReviewTaskId NUMBER, ReviewTaskResultTypeId NUMBER, CreationDate TIME, RejectionReasonId NUMBER, Comment CLOB)
CREATE TABLE FlagTypes (Id NUMBER, Name CLOB, Description CLOB)
CREATE TABLE Users (Id NUMBER, Reputation NUMBER, CreationDate TIME, DisplayName CLOB, LastAccessDate TIME, WebsiteUrl CLOB, Location CLOB, AboutMe CLOB, Views NUMBER, UpVotes NUMBER, DownVotes NUMBER, ProfileImageUrl CLOB, EmailHash CLOB, AccountId NUMBER)
CREATE TABLE PostNotices (Id NUMBER, PostId NUMBER, PostNoticeTypeId NUMBER, CreationDate TIME, DeletionDate TIME, ExpiryDate TIME, Body CLOB, OwnerUserId NUMBER, DeletionUserId NUMBER)
CREATE TABLE SuggestedEdits (Id NUMBER, PostId NUMBER, CreationDate TIME, ApprovalDate TIME, RejectionDate TIME, OwnerUserId NUMBER, Comment CLOB, Text CLOB, Title CLOB, Tags CLOB, RevisionGUID other)
CREATE TABLE PostNoticeTypes (Id NUMBER, ClassId NUMBER, Name CLOB, Body CLOB, IsHidden BOOLEAN, Predefined BOOLEAN, PostNoticeDurationId NUMBER)
CREATE TABLE PostTypes (Id NUMBER, Name CLOB)
CREATE TABLE PostHistoryTypes (Id NUMBER, Name CLOB)
CREATE TABLE ReviewTaskResultTypes (Id NUMBER, Name CLOB, Description CLOB)
CREATE TABLE PostsWithDeleted (Id NUMBER, PostTypeId NUMBER, AcceptedAnswerId NUMBER, ParentId NUMBER, CreationDate TIME, DeletionDate TIME, Score NUMBER, ViewCount NUMBER, Body CLOB, OwnerUserId NUMBER, OwnerDisplayName CLOB, LastEditorUserId NUMBER, LastEditorDisplayName CLOB, LastEditDate TIME, LastActivityDate TIME, Title CLOB, Tags CLOB, AnswerCount NUMBER, CommentCount NUMBER, FavoriteCount NUMBER, ClosedDate TIME, CommunityOwnedDate TIME, ContentLicense CLOB)
CREATE TABLE PostFeedback (Id NUMBER, PostId NUMBER, IsAnonymous BOOLEAN, VoteTypeId NUMBER, CreationDate TIME)
CREATE TABLE VoteTypes (Id NUMBER, Name CLOB)
CREATE TABLE Comments (Id NUMBER, PostId NUMBER, Score NUMBER, Text CLOB, CreationDate TIME, UserDisplayName CLOB, UserId NUMBER, ContentLicense CLOB)
CREATE TABLE Votes (Id NUMBER, PostId NUMBER, VoteTypeId NUMBER, UserId NUMBER, CreationDate TIME, BountyAmount NUMBER)
CREATE TABLE Badges (Id NUMBER, UserId NUMBER, Name CLOB, Date TIME, Class NUMBER, TagBased BOOLEAN)
CREATE TABLE PostHistory (Id NUMBER, PostHistoryTypeId NUMBER, PostId NUMBER, RevisionGUID other, CreationDate TIME, UserId NUMBER, UserDisplayName CLOB, Comment CLOB, Text CLOB, ContentLicense CLOB)
CREATE TABLE ReviewRejectionReasons (Id NUMBER, Name CLOB, Description CLOB, PostTypeId NUMBER)
CREATE TABLE PendingFlags (Id NUMBER, FlagTypeId NUMBER, PostId NUMBER, CreationDate TIME, CloseReasonTypeId NUMBER, CloseAsOffTopicReasonTypeId NUMBER, DuplicateOfQuestionId NUMBER, BelongsOnBaseHostAddress CLOB)
CREATE TABLE ReviewTasks (Id NUMBER, ReviewTaskTypeId NUMBER, CreationDate TIME, DeletionDate TIME, ReviewTaskStateId NUMBER, PostId NUMBER, SuggestedEditId NUMBER, CompletedByReviewTaskId NUMBER)
CREATE TABLE PostLinks (Id NUMBER, CreationDate TIME, PostId NUMBER, RelatedPostId NUMBER, LinkTypeId NUMBER)
CREATE TABLE SuggestedEditVotes (Id NUMBER, SuggestedEditId NUMBER, UserId NUMBER, VoteTypeId NUMBER, CreationDate TIME, TargetUserId NUMBER, TargetRepChange NUMBER)
CREATE TABLE Tags (Id NUMBER, TagName CLOB, Count NUMBER, ExcerptPostId NUMBER, WikiPostId NUMBER)

Self-duplicates with no answers (list of stub Qs). Find duplicate unanswered questions where OP from the stub post (source) is the same OP as from the destination post (master/target). Usually, duplicates serve a purpose of linking nearly identical posts in scope so the best/canonical answer can be found. They are useful because since people can ask related questions with different wording, there are more chances the result of a search leading to one of the dupes (and then, the canonical answer). HOWEVER, duplicate questions asked by the same OP* are likely to have the same wording and therefore, the corresponding stubs are useless to the site. Those should be purged (flag for moderator attention or cast a delete vote, after confirming it is a useless question)! *Usually this happens because OP asks, then nobody answers, then he/she asks the same Q again instead of improving the first one (there are exceptions, this is why results from the query should be reviewed carefully).
WITH stub_list AS (SELECT p.Id, p.Score, p.OwnerUserId, pl.RelatedPostId FROM Posts AS p JOIN PostLinks AS pl ON pl.PostId = p.Id WHERE p.PostTypeId = 1 AND EXISTS(SELECT * FROM PostHistory AS ph WHERE ph.PostId = p.Id AND ph.PostHistoryTypeId IN (10, 37)) AND pl.LinkTypeId = 3 AND p.AnswerCount = 0) SELECT s.Id AS "post_link", s.Score FROM stub_list AS s JOIN Posts AS p ON p.Id = s.RelatedPostId WHERE s.OwnerUserId = p.OwnerUserId ORDER BY s.Score
WITH "_u_0" AS (SELECT "ph"."PostId" AS "_u_1" FROM "PostHistory" "ph" WHERE "ph"."PostHistoryTypeId" IN (10, 37) GROUP BY "ph"."PostId") SELECT "p_2"."Id" AS "post_link", "p_2"."Score" FROM "Posts" "p_2" LEFT JOIN "_u_0" "_u_0" ON "_u_0"."_u_1" = "p_2"."Id" JOIN "PostLinks" "pl" ON "p_2"."Id" = "pl"."PostId" AND "pl"."LinkTypeId" = 3 JOIN "Posts" "p" ON "p"."Id" = "pl"."RelatedPostId" AND "p"."OwnerUserId" = "p_2"."OwnerUserId" WHERE "p_2"."AnswerCount" = 0 AND "p_2"."PostTypeId" = 1 AND NOT "_u_0"."_u_1" IS NULL ORDER BY "p_2"."Score"