SQL - 另一個子查詢

SELECT 
    * 
FROM 
    (
     SELECT 
      qu.job_id AS `qu_job_id` , qu.engineer_id, qu.id AS `quote_id` , jb.author, jb.job_id, jb.job_title, SUBSTRING(jb.job_description, 1, 200) AS `short_description` , jb.image_ref, jb.timestamp 
     FROM 
      jobs AS `jb` 
     LEFT JOIN 
      quotes AS `qu` 
     ON 
     qu.job_id = jb.job_id 
     WHERE 
     jb.author = " . ID . " 
     GROUP BY 
     jb.job_id 
     ORDER BY 
     jb.timestamp DESC 
    ) AS `jobs` 
    LEFT JOIN 
    (
     SELECT 
     COUNT(id) AS `total_replies` , job_id 
     FROM 
     quote_comments 
     WHERE 
     job_id = jobs.job_id 
    ) AS `replies` 
    ON 
     replies.job_id = jobs.job_id

我的問題使用結果從子查詢是否有可能（以上不作爲是工作）把這個結果從第一子查詢，以防止在第二比較？（即job_id = jobs.job_id）SQL - 另一個子查詢

問候

編輯

（這裏作爲評論有更多的空間）

SELECT 
    qu.engineer_id, 
    qu.id AS `quote_id`, 
    jb.author, 
    jb.job_id, 
    jb.job_title, 
    SUBSTRING(jb.job_description, 1, 200) AS `short_description` , 
    jb.image_ref, 
    jb.timestamp, 
    count(qu.id) AS comment_count 
FROM 
    " . JOBS . " AS `jb` 
LEFT JOIN 
    " . QUOTES . " AS `qu` 
ON 
    qu.job_id = jb.job_id 
WHERE 
    jb.author = " . ID . " 
GROUP BY 
    jb.job_id, 
    qu.engineer_id, 
    qu.id, 
    jb.author, 
    jb.job_title, 
    SUBSTRING(jb.job_description, 1, 200), 
    jb.image_ref, 
    jb.timestamp 
ORDER BY 
    jb.timestamp DESC

我最初的問題是不正確略。我實際上想要得到報價的數量，而不是報價評論。

上述建議在下面看起來似乎乍一看，但它返回的工作有多個報價submited×次數與每個報價計數爲1。有任何想法嗎？

來源

2012-01-27 Phil Jackson

是的，它是可能的。首先，你不能在子查詢中使用ORDER BY。這是你得到的錯誤嗎？ – 2012-01-27 20:06:42

它看起來像你試圖得到一份工作，得到任何工作報價（或沒有），以及作業的報價評論數。如果這是正確的，我想我知道答案。 – Hasteur 2012-01-27 20:11:37

我想要做的是從3個表中獲取信息。所有這三個在comman，job_id和author_id中都有兩個東西。我想要獲得所有工作，並且還要獲得1個查詢中每個工作收到的評論數量。（p.s.順序工作正常） – 2012-01-27 20:11:44

SELECT 
    qu.engineer_id, 
    qu.id AS `quote_id`, 
    jb.author, 
    jb.job_id, 
    jb.job_title, 
    SUBSTRING(jb.job_description, 1, 200) AS `short_description` , 
    jb.image_ref, 
    jb.timestamp, 
    count(qc.id) AS comment_count 
FROM 
    jobs AS `jb` 
LEFT JOIN quotes AS `qu` ON qu.job_id = jb.job_id 
LEFT JOIN quote_comments AS `qc` ON qu.job_id = qc.job_id 
WHERE 
    jb.author = " . ID . " 
GROUP BY 
    jb.job_id, 
    qu.engineer_id, 
    qu.id, 
    jb.author, 
    jb.job_title, 
    SUBSTRING(jb.job_description, 1, 200) 
    jb.image_ref, 
    jb.timestamp 
ORDER BY 
    jb.timestamp DESC

這將消除子查詢解析並使您的總體查詢運行得更快。我刪除了報價工作ID，因爲我們正在加入，因此只需要拉一次。我注意到我們直接從工作中拼接引用評論。您可能希望通過報價，讓你看到有多少評論每帖有多少報價評論，而不是有整體的工作聯繫起來

來源

2012-01-27 20:23:21 Hasteur

感謝上述小周，並像一個魅力工作。謝謝 – 2012-01-27 20:32:09

等等，不，我不挑剔，因爲它沒有完全回答，我會在問題中解釋更多。 – 2012-01-27 20:37:44

如果你將一個表'A'加入到2個表'B'和'C'中，這兩個表都與A有一對多的關係，然後你用A.something'做一個'group，在集合函數中會得到錯誤的結果。 – 2012-01-27 23:16:25

SELECT 
    jb.author, 
    jb.job_id, 
    jb.job_title, 
    SUBSTRING(jb.job_description, 1, 200) AS `short_description` , 
    jb.image_ref, 
    jb.timestamp, 
    count(qu.id) AS quote_count 
FROM 
    jobs AS `jb` 
LEFT JOIN quotes AS `qu` ON qu.job_id = jb.job_id 
WHERE 
    jb.author = " . ID . " 
GROUP BY 
    jb.job_id, 
    jb.author, 
    jb.job_title, 
    SUBSTRING(jb.job_description, 1, 200) 
    jb.image_ref, 
    jb.timestamp 
ORDER BY 
    jb.timestamp DESC

這將拉動由ID撰寫，然後做的工作對提交的工作報價進行計數。 Unfortunateley獲得報價作業的數量，你必須從報價表

來源

2012-01-27 20:48:00 Hasteur

編輯您的第一個查詢離開過工程師ID和報價ID：

SELECT 
    * 
FROM 
    ( SELECT 
      qu.job_id AS `qu_job_id` , qu.engineer_id, qu.id AS `quote_id`, 
      jb.author, jb.job_id, jb.job_title, 
      SUBSTRING(jb.job_description, 1, 200) AS `short_description`, 
      jb.image_ref, jb.timestamp 
     FROM 
      jobs AS `jb` 
     LEFT JOIN 
      quotes AS `qu` 
     ON 
      qu.job_id = jb.job_id 
     WHERE 
      jb.author = " . ID . " 
     GROUP BY 
      jb.job_id 
           --- ORDER BY   --- not needed 
           --- jb.timestamp DESC --- here 
    ) AS `jobs` 
    LEFT JOIN 
    (
     SELECT 
      COUNT(*) AS `total_replies` , job_id 
     FROM 
      quote_comments 
           --- WHERE 
           --- job_id = jobs.job_id 
     GROUP BY    --- replacing the WHERE 
      job_id    --- with a GROUP BY 
    ) AS `replies` 
    ON 
     replies.job_id = jobs.job_id 
ORDER BY      --- order clause 
    timestamp DESC    --- moved here

來源

2012-01-27 21:21:28

SQL - 另一個子查詢

回答

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