使用多个 JOINS 将 MYSQL 查询转换为 HQL

Question

每个人。

我正在使用 grails 3.3.0.M2 框架和 mysql 作为数据源，以下 sql 查询按预期工作

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 JOIN 翻译成 HQL 但我得到了错误的结果，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理解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

现在我正在尝试以下查询：

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
        INNER JOIN
    User u
        INNER JOIN
    UserCoordination uc
        INNER JOIN
    Coordination c
WHERE
    MONTH(t.dateCreated) = :month
GROUP BY 1

但我收到 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException 并带有导致的消息 您的 SQL 语法有错误；检查与您的 MySQL 服务器版本相对应的手册，以在第 1 行的“inner join user_coordinations usercoordi2_ on inner join coordinates coordinat”附近使用正确的语法

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

//按 1 分组

你在上面缺少的东西更像是你需要的，你需要的 select new map(i.item as item... 如果您将此基础知识与您所拥有的以及我尝试做的进行比较，您就会明白为什么会出现错误。

不确定你的 group by 它应该是 group by something。不确定内连接是否只是指连接，如果是这种情况，则忽略所有左连接，因为左连接尝试连接并获取任何空的 hasMany 关系等。