使用多個連接將MYSQL查詢轉換爲HQL

Question

everyone。

我使用Grails與MySQL 3.3.0.M2框架作爲數據源下面的SQL查詢工作正常

SELECT 
    c.name, 
    SUM(CASE 
     WHEN t.status = 'open' THEN 1 
     ELSE 0 
    END) 'open', 
    SUM(CASE 
     WHEN t.status = 'pending' THEN 1 
     ELSE 0 
    END) 'in progress', 
    SUM(CASE 
     WHEN t.status = 'closed' THEN 1 
     ELSE 0 
    END) 'closed' 
FROM 
    tickets t 
     INNER JOIN 
    users u ON t.user_id = u.id 
     INNER JOIN 
    user_coordinations uc ON uc.user_id = u.id 
     INNER JOIN 
    coordinations c ON c.id = uc.coordination_id 
GROUP BY 1 

我使用隱式連接翻譯成HQL，但我得到錯誤的結果，這裏是HQL查詢：

SELECT 
    c.name, 
    SUM(CASE 
     WHEN t.status = 'open' THEN 1 
     ELSE 0 
    END), 
    SUM(CASE 
     WHEN t.status = 'pending' THEN 1 
     ELSE 0 
    END), 
    SUM(CASE 
     WHEN t.status = 'closed' THEN 1 
     ELSE 0 
    END) 
FROM 
    Ticket t, User u, UserCoordination uc, Coordination c 
WHERE 
    MONTH(t.dateCreated) = :month 
GROUP BY 1 

爲了得到正確的結果堆棧溢出用戶幫助我明白，查詢需要使用顯式連接，這裏的問題是：Group by a field that does not belongs to the consulted table

現在我用下面的查詢嘗試：

SELECT 
    c.name, 
    SUM(CASE 
     WHEN t.status = 'open' THEN 1 
     ELSE 0 
    END), 
    SUM(CASE 
     WHEN t.status = 'pending' THEN 1 
     ELSE 0 
    END), 
    SUM(CASE 
     WHEN t.status = 'closed' THEN 1 
     ELSE 0 
    END) 
FROM 
    Ticket t 
     INNER JOIN 
    User u 
     INNER JOIN 
    UserCoordination uc 
     INNER JOIN 
    Coordination c 
WHERE 
    MONTH(t.dateCreated) = :month 
GROUP BY 1 

但我得到一個com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException與消息引起您有一個錯誤的SQL語法;檢查對應於你的MySQL服務器版本的手冊正確的語法使用近「內部聯接user_coordinations usercoordi2_的內連接配位coordinat」在行1

感謝您的幫助和時間

Answer 1

SELECT new map(
    c.name as name, 
(CASE 
     WHEN t.status = 'open' THEN 1 
     ELSE 0 
    END) as open, 
(CASE 
     WHEN t.status = 'pending' THEN 1 
     ELSE 0 
    END) as pending, 
(CASE 
     WHEN t.status = 'closed' THEN 1 
     ELSE 0 
    END) as closed, 
    SUM(open) as openSum, 
    SUM(pending) as pendingSum, 
    SUM(closed) as closedSum 
) 
FROM 
    Ticket t 
     left join t.user u left join u.userCoordination uc left join uc.coordination c 
WHERE 
    MONTH(t.dateCreated) = :month 

// GROUP BY 1

你有過什麼地段缺少上述更像是你需要什麼，你需要 select new map(i.item as item...如果你跟你有什麼，什麼我試圖做的，你可以看到爲什麼你有錯誤，比較這個基礎。

不確定你的團隊應該由某物組合。不確定由內部連接，如果你只是意味着一個連接，如果是這樣的話，由於離開連接嘗試連接並獲得任何null hasMany關係等情況，所以留下所有的左連接