如何獲得最近對每篇文章的評論？而分組它顯示的意見第一條記錄

Question

SELECT * FROM （ comments ） LEFT JOIN posts ON posts。 id = comments。 case_id WHERE comments。 'user_id ='8' GROUP BY comments。 case_id ORDER BY comments。 created_date DESC我的編碼是這一個。如何獲得最近對每篇文章的評論？同時將其分組顯示第一條記錄

Answer 1

SELECT * 
FROM ( SELECT comments.* 
     FROM comments 
     INNER JOIN comment2article USING (comment_id) 
     WHERE comment2article.article_d= ID_of_article 
    ) MAIN_TABLE 
LEFT JOIN (SELECT comments.* 
      FROM comments 
      INNER JOIN comment2article USING (comment_id) 
      WHERE comment2article.article_d= ID_of_article 
     ) DUMMY_TABLE ON (MAIN_TABLE.comment_id = DUMMY_TABLE.comment_id AND MAIN_TABLE.created < DUMMY_TABLE.created) 
WHERE DUMMY_TABLE.comment_id IS NULL; 

試試上面的查詢。

希望這會幫助你。