如何在mysql搜索JOIN查詢期間檢查行是否存在？

Question

我有這個有效的sql搜索查詢，但僅當投票表中存在投票時才有效。

mysql_query("SELECT m.Title, r.Subject, SUM(v.IsGood) AS Good, SUM(v.IsBad) AS Bad
    FROM Movies m
        JOIN Reviews r
            ON m.ID=r.MovieID
        JOIN Votes v
        ON r.ID=v.ReviewID
    WHERE (m.Title LIKE '%" . $search . "%' OR r.Subject LIKE '%" . $search . "%')
        GROUP BY m.Title, r.Subject
    ORDER BY SUM(v.IsGood) DESC, SUM(v.IsBad) ASC LIMIT 10")

因此，我將其更改為以下內容，以便無論是否有0票，它都應該仍然顯示。 但這並沒有取得任何結果，有人可以告訴我我做錯了什么嗎？

mysql_query("SELECT m.Title, r.Subject, COUNT(v.ReviewID) AS Rvotes, SUM(v.IsGood) AS Good, SUM(v.IsBad) AS Bad
    FROM Movies m
        JOIN Reviews r
            ON m.ID=r.MovieID
        JOIN Votes v
        ON r.ID=v.ReviewID
    WHERE (m.Title LIKE '%" . $search . "%' OR r.Subject LIKE '%" . $search . "%')
        GROUP BY m.Title, r.Subject, v.ReviewID
            HAVING Rvotes >= 0
    ORDER BY SUM(v.IsGood) DESC, SUM(v.IsBad) ASC LIMIT 10")

Answer 1

假設即使在投票表中不存在投票的情況下也要獲得結果，請LEFT JOIN 投票表。

mysql_query("SELECT m.Title, r.Subject, SUM(v.IsGood) AS Good, SUM(v.IsBad) AS Bad
    FROM Movies m
        JOIN Reviews r
            ON m.ID=r.MovieID
        LEFT JOIN Votes v
        ON r.ID=v.ReviewID
    WHERE (m.Title LIKE '%" . $search . "%' OR r.Subject LIKE '%" . $search . "%')
        GROUP BY m.Title, r.Subject
    ORDER BY SUM(v.IsGood) DESC, SUM(v.IsBad) ASC LIMIT 10")

注意：我已經修改了您的初始查詢（不是第二個查詢），因為您說它仍然沒有提供您想要的內容。