如何通過基於分片ID的另一個表的計數來排序SQL查詢的結果？

我有一個從數據庫中提取帖子的SQL查詢。一切工作正常，但現在我需要按每個帖子的評論數量排序結果。評論是在一個單獨的表格上，他們有一個post_id列將其鏈接到該帖子。我需要根據評論表的數量來根據分片ID排序。我嘗試了一切，但每次嘗試添加一些內容到我的查詢時，它都會停止運行並將我的頁面留空。我需要幫助才能知道將其他JOIN語句放在哪裏。這是我的查詢：如何通過基於分片ID的另一個表的計數來排序SQL查詢的結果？

$union = "UNION ALL 
       ( 
        SELECT DISTINCT wallposts.p_id,wallposts.is_profile_notes,wallposts.times_viewed,wallposts.columnTimesShared, 
        wallposts.marked,wallposts.secure_id,wallposts.reshared,wallposts.group_id, 
        wallposts.totaluploads,wallposts.WallUploadID,wallposts.type, 
        wallposts.value,wallposts.media,wallposts.youtube,wallposts.post_type, 
        wallposts.privacy,wallposts.tagedpersons,wallposts.with_friends_tagged,wallposts.emotion_head,wallposts.selected_emotion,wallposts.title, 
        wallposts.url,wallposts.description,wallposts.cur_image, 
        wallposts.uip,wallposts.likes,wallposts.userid, 
        wallposts.posted_by,wallposts.post as postdata,wallusers.*, 
        UNIX_TIMESTAMP() - wallposts.date_created AS TimeSpent, 

        PosterTable.mem_pic as posterPic, PosterTable.gender as posterGender,PosterTable.oauth_uid as poster_oauth_uid, PosterTable.username as posterUsername, 
        PosterTable.mem_fname as posterFname,PosterTable.work as posterWork, 
        PosterTable.mem_lname as posterLname,walllikes_track.id as PostLikeFound,wallposts.date_created 

        FROM 
         wallusers,wallusers as PosterTable, wallposts 
        LEFT JOIN walllikes_track 
         ON wallposts.p_id = walllikes_track.post_id AND walllikes_track.member_id = ".$user_id." 
        WHERE 
         wallusers.active = 1 
        AND 
         PosterTable.active = 1 
        AND 
         wallposts.group_id IN (".$groups.") 
        AND 
         wallposts.group_id != 0 
        AND 
         PosterTable.mem_id = wallposts.posted_by 
        AND 
         wallposts.marked < ".$this->flagNumber." 
        AND 
         wallusers.mem_id = wallposts.posted_by) ";

評論表被稱爲wallcomments，它有一個名爲post_id的列。我知道我需要使用JOIN和COUNT，但我不知道把它放在我現在的代碼中。

來源

2017-04-26 Romeo Hennessy

將一個額外的連接添加到子查詢中，該子查詢可以查找每個帖子的評論計數並使用它。我無法給出確切的答案，因爲缺少很多細節，而且您的查詢亂七八糟。 –

我應該在哪裏插入JOIN？這是我的困境。每當我對查詢進行任何更改時。它完全停止運行。 –

是的，因爲你的查詢非常龐大，難以理解，問題也是如此。下一次，通過展示您的問題的最小示例來提出更好的問題。沒有人可以重現您現在的查詢，因爲甚至沒有任何數據可用。 –

試試此查詢，我沒有運行，但我更新了它。

SELECT wallposts.p_id,wallposts.is_profile_notes,wallposts.times_viewed,wallposts.columnTimesShared, 
       wallposts.marked,wallposts.secure_id,wallposts.reshared,wallposts.group_id, 
       wallposts.totaluploads,wallposts.WallUploadID,wallposts.type, 
       wallposts.value,wallposts.media,wallposts.youtube,wallposts.post_type, 
       wallposts.privacy,wallposts.tagedpersons,wallposts.with_friends_tagged,wallposts.emotion_head,wallposts.selected_emotion,wallposts.title, 
       wallposts.url,wallposts.description,wallposts.cur_image, 
       wallposts.uip,wallposts.likes,wallposts.userid, 
       wallposts.posted_by,wallposts.post as postdata,wallusers.*, 
       UNIX_TIMESTAMP() - wallposts.date_created AS TimeSpent, 

       PosterTable.mem_pic as posterPic, PosterTable.gender as posterGender,PosterTable.oauth_uid as poster_oauth_uid, PosterTable.username as posterUsername, 
       PosterTable.mem_fname as posterFname,PosterTable.work as posterWork, 
       PosterTable.mem_lname as posterLname,walllikes_track.id as PostLikeFound,wallposts.date_created 

       FROM 
        wallusers,wallusers as PosterTable, wallposts 
       WHERE 
        wallusers.active = 1 
       AND 
        PosterTable.active = 1 
       AND 
        wallposts.group_id IN (".$groups.") 
       AND 
        wallposts.group_id != 0 
       AND 
        PosterTable.mem_id = wallposts.posted_by 
       AND 
        wallposts.marked < ".$this->flagNumber." 
       AND 
        wallusers.mem_id = wallposts.posted_by) " AND wallposts.p_id = walllikes_track.post_id AND walllikes_track.member_id = ".$user_id.";

來源

2017-04-26 06:23:27

謝謝您的回答，但您更新了哪部分？我沒有看到任何改變。我沒有看到引用評論表的任何內容。評論表稱爲wallcomments，它有一個名爲post_id的列。 –

我刪除了** UNION ALL ** ** JOIN **和** ON **關鍵字，因爲SQL允許您在不使用JOIN的情況下連接表。例如， SELECT e.id，e.did，e.name，e.sal，d.department，FROM employee e，department d WHERE e.did = d.id： –

更可讀的查詢可能是這樣的......

至少這樣我們就會有機會。

SELECT DISTINCT p.p_id 
       , p.is_profile_notes 
       , p.times_viewed 
       , p.columnTimesShared 
       , p.marked 
       , p.secure_id 
       , p.media... 
      FROM wallposts p...

來源

2017-04-26 07:16:44 Strawberry

如何通過基於分片ID的另一個表的計數來排序SQL查詢的結果？

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