Post CreationDate ไม่ใช่ค่าเฉพาะ ไม่จำเป็นต้องใช้ตารางทั้งหมด
Post CreationDate is not unique.It is not neccessary to use all the tables.
 Posts:  Id [ number]  PostTypeId [ number]  AcceptedAnswerId [ number]  ParentId [ number]  CreationDate [ time]  DeletionDate [ time]  Score [ number]  ViewCount [ number]  Body [ text]  OwnerUserId [ number]  OwnerDisplayName [ text]  LastEditorUserId [ number]  LastEditorDisplayName [ text]  LastEditDate [ time]  LastActivityDate [ time]  Title [ text]  Tags [ text]  AnswerCount [ number]  CommentCount [ number]  FavoriteCount [ number]  ClosedDate [ time]  CommunityOwnedDate [ time]  ContentLicense [ text] 
SELECT p.Id AS "a_id", twn.Id AS "b_id", p.CreationDate, p.PostTypeId AS "a_type", twn.PostTypeId AS "b_type", p.Tags AS "a_tags", twn.Tags AS "b_tags", p.Title AS "a_title", twn.Title AS "b_title" FROM Posts AS p INNER JOIN Posts AS twn ON (p.CreationDate = twn.CreationDate AND p.Id < twn.Id) ORDER BY p.CreationDate, p.Id, twn.Id LIMIT 20000