进行自我左连接时意外左

Question

我试图在同一张桌子上多次进行自我左连接。每当我执行此查询时，我都会遇到异常。

类 org.hibernate.hql.internal.ast.QuerySyntaxException 消息意外标记：LEFT 靠近第 13 行第 33 列

Query query = null
        def hql = $/
                SELECT
                    c1.id,
                    c1.parentId,
                    c1.navDepth,
                    c1.navOrder,
                    c1.title,
                    c1.fileName,
                    // aliasing filenamepath column as filepath.
                    REPLACE(c1.fileNamePath, 'home/', '') AS filepath
                FROM Content AS c1

                WHERE 0 = 0
                LEFT JOIN Content AS c2
                ON c1.col1 = c2.fileNameLookup
                AND c1.col1 = c2.col1

                LEFT JOIN Content AS c3
                ON c1.col2 = c3.fileNameLookup
                AND c1.col2 = c3.col2

                LEFT JOIN Content AS c4
                ON c1.col3 = c4.fileNameLookup
                AND c1.col3 = c4.col3

                LEFT JOIN Content AS c5
                ON c1.col4 = c5.fileNameLookup
                AND c1.col4 = c5.col4

                LEFT JOIN Content AS c6
                ON c1.col5 = c6.fileNameLookup
                AND c1.col5 = c6.col5

                LEFT JOIN Content AS c7
                ON c1.col6 = c7.fileNameLookup
                AND c1.col6 = c7.col6

                LEFT JOIN Content AS c8
                ON c1.col7 = c8.fileNameLookup
                AND c1.col7 = c8.col7

                LEFT JOIN Content AS c9
                ON c1.col8 = c9.fileNameLookup
                AND c1.col8 = c9.col8

                LEFT JOIN Content AS c10
                ON c1.col9 = c10.fileNameLookup
                AND c1.col9 = c10.col9

                AND c1.isNavItem = 1
                GROUP BY c1.id
                ORDER BY c1.navDepth, c1.navOrder
                /$
                //def result = Content.executeQuery(hql)
        query = Content.executeQuery(hql).setResultTransformer(AliasToEntityMapResultTransformer.INSTANCE)
                .addScalar("filepath", new StringType())
        List<Map<String,Object>> result = query.list()
        return result

谁能告诉我我做错了什么，我怎样才能让它工作？

Answer 1

1. WHERE 放错地方了：

   FROM 
   WHERE 0 = 0
   LEFT JOIN Content AS c2
   

   应该是：

   FROM
   LEFT JOIN
   LEFT JOIN
   ...
   WHERE
   GROUP BY
   ORDER BY
   

2. 在您的查询中没有要设置的 filepath 参数，如果它必须在 WHERE 子句中而不是在 SELECT 子句中：

   addScalar("filepath", new StringType())
   

3. 您编写了一个带有 LEFT JOINS 和 ON 子句的 SQL 查询，但这是本机 SQL 查询语法。在 HQL 中，您加入可导航实体关联，并且没有 HQL ON 子句。

   要模拟 ON 子句，您需要使用 the with directive：

   from Cat as cat
       left join cat.kittens as kitten
           with kitten.bodyWeight > 10.0
   

4. 先尝试不使用变压器。只需执行查询并让它首先返回一个列表。如果可行，请尝试使用变压器。如果不是，您的查询语法仍然存在问题。