使用多个连接将MYSQL查询转换为HQL

Question

everyone。

我使用Grails与MySQL 3.3.0.M2框架作为数据源下面的SQL查询工作正常

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 

我使用隐式连接翻译成HQL，但我得到错误的结果，这里是HQL查询：

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 

为了得到正确的结果堆栈溢出用户帮助我明白，查询需要使用显式连接，这里的问题是：Group by a field that does not belongs to the consulted table

现在我用下面的查询尝试：

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 

但我得到一个com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException与消息引起您有一个错误的SQL语法;检查对应于你的MySQL服务器版本的手册正确的语法使用近“内部联接user_coordinations usercoordi2_的内连接配位coordinat”在行1

感谢您的帮助和时间

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

你有过什么地段缺少上述更像是你需要什么，你需要 select new map(i.item as item...如果你跟你有什么，什么我试图做的，你可以看到为什么你有错误，比较这个基础。

不确定你的团队应该由某物组合。不确定由内部连接，如果你只是意味着一个连接，如果是这样的话，由于离开连接尝试连接并获得任何null hasMany关系等情况，所以留下所有的左连接