如何計算JOIN中的行數？

我有四個表，我想要使用JOIN與表「pro_quiz_statistic_ref」結合使用。除了一張桌子外，所有的桌子都加入了，這就是「pro_quiz_stastic」。如何計算JOIN中的行數？

表「pro_quiz_statistic_ref」持有用戶參加了所有的測驗。

在pro_quiz_statistic有從每次測驗，當然有statistic_ref_id以確定其所屬的競猜答案10的記錄。我想使用相同的statistic_ref_id來計算表「pro_quiz_statistic」中的「correct_count」列。

我有這個疑問：

$results_quiz = $pdo->query("SELECT 
    sr.statistic_ref_id, 
    sr.quiz_id, 
    sr.user_id, 
    sr.total_time, 
    qm.name AS q_name, 
    qm.category_id, 
    qm.subcategory_id, 
    sc.sub_category_id, 
    sc.sub_category_name AS quiz_type, 
    pl.time, 
    pl.points, 
    qs.correct_count AS count_correct 
    FROM pro_quiz_statistic_ref AS sr 
    JOIN pro_quiz_master qm ON qm.id = sr.quiz_id 
    JOIN pro_quiz_subcategory sc ON sc.sub_category_id = qm.subcategory_id 
    JOIN user_points_log pl ON pl.quiz_id = sr.quiz_id AND pl.user_id = '$get_id' 
    JOIN pro_quiz_statistic qs ON qs.statistic_ref_id = sr.statistic_ref_id 
    WHERE sr.user_id = '$get_id' ORDER BY qm.name ASC");

有了上面代碼中它打印出該用戶已參加了「pro_quiz_statistic」上市* 10個回答所有提問

我試圖把它寫像

COUNT(qs.correct_count) AS count_correct

但它只打印出一行。順便說一句：它也被user_id過濾。

我想使用JOIN的原因是因爲有更多的

有人可以幫助我？

問候

肯尼斯

-------- ---------修訂

我結束了本該是工作得很好：

$results_quiz = $pdo->query("SELECT 
    sr.statistic_ref_id, 
    sr.quiz_id, 
    sr.user_id, 
    sr.total_time, 
    qm.name AS q_name, 
    qm.category_id, 
    qm.subcategory_id, 
    sc.sub_category_id, 
    sc.sub_category_name AS quiz_type, 
    pl.time, 
    pl.points, 
    COUNT(qs.correct_count) AS count_correct 
    FROM pro_quiz_statistic_ref AS sr 
    JOIN pro_quiz_master qm ON qm.id = sr.quiz_id 
    JOIN pro_quiz_subcategory sc ON sc.sub_category_id = qm.subcategory_id 
    JOIN user_points_log pl ON pl.quiz_id = sr.quiz_id AND pl.user_id = '$get_id' 
    JOIN pro_quiz_statistic qs ON qs.statistic_ref_id = sr.statistic_ref_id 
    WHERE 
    sr.user_id = '$get_id' AND 
    qs.correct_count = '1' 
    GROUP BY  
    sr.statistic_ref_id, 
    qs.correct_count 
    ORDER BY qm.name ASC");

來源

2017-01-14 Kenneth

如果你需要一個像數（..），你應該通過語句中使用一組聚合函數

$results_quiz = $pdo->query("SELECT 
     sr.statistic_ref_id, 
     sr.quiz_id, 
     sr.user_id, 
     sr.total_time, 
     qm.name AS q_name, 
     qm.category_id, 
     qm.subcategory_id, 
     sc.sub_category_id, 
     sc.sub_category_name AS quiz_type, 
     pl.time, 
     pl.points, 
     count(qs.correct_count)AS count_correct 
     FROM pro_quiz_statistic_ref AS sr 
     JOIN pro_quiz_master qm ON qm.id = sr.quiz_id 
     JOIN pro_quiz_subcategory sc ON sc.sub_category_id = qm.subcategory_id 
     JOIN user_points_log pl ON pl.quiz_id = sr.quiz_id AND pl.user_id = '$get_id' 
     JOIN pro_quiz_statistic qs ON qs.statistic_ref_id = sr.statistic_ref_id 
     WHERE sr.user_id = '$get_id' 
     GROUP BY  
     sr.statistic_ref_id, 
     sr.quiz_id, 
     sr.user_id, 
     sr.total_time, 
     qm.name, 
     qm.category_id, 
     qm.subcategory_id, 
     sc.sub_category_id, 
     sc.sub_category_name AS quiz_type, 
     pl.time, 
     pl.point 
     ORDER BY qm.name ASC");

來源

2017-01-14 17:54:21 scaisEdge

非常感謝你scaisEdge :-) – Kenneth

@Kenneth我。看到你只是簡單地renoved一些（無用的專欄從組），以及如果我的回答是正確的，請將其標記爲已接受...看看這裏如何 http://meta.stackexchange.com/questions/5234/how-does-accepting -an-answer-work – scaisEdge

這樣做..我已經發布了另一個問題，我已經與計數哪些與此有關：http://stackoverflow.com/questions/41656159/make-a-count-on-join-tables – Kenneth

如何計算JOIN中的行數？

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