java - 进行自左连接时意外离开

Question

我正在尝试多次在同一张表上进行自左连接。每当我执行这个查询时，我都会遇到异常。

org.hibernate.hql.internal.ast.QuerySyntaxException 类消息意外标记:第 13 行第 33 列附近的 LEFT

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

任何人都可以让我知道我做错了什么，我怎样才能让它工作？

Answer 1

1. WHERE 放错了位置:

   FROM 
   WHERE 0 = 0
   LEFT JOIN Content AS c2
   

   应该是:

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

2. 查询中没有要设置的文件路径参数，如果它必须位于 WHERE 子句中而不是 SELECT 子句中:

   addScalar("filepath", new StringType())
   

3. 您编写了一个包含 LEFT JOINS 和 ON 子句的 SQL 查询，但这是 native 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. 首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即可。如果有效，请尝试使用变压器。如果没有，您的查询语法仍然存在问题。