window 函数字段的别名在 HAVING 和 WHERE 子句中使用时导致 "not found" 错误

Question

考虑以下 BigQuery 查询：

SELECT
    tn.object AS object_alias,
    tn.attribute1 AS attribute1_alias,
    tn.attribute2 AS attribute2_alias,
    tn.score AS score_alias,
    ROW_NUMBER() OVER (PARTITION BY attribute1_alias, attribute2_alias ORDER BY score_alias DESC) AS row_num_alias
FROM
    [datasetName.tableName] tn
HAVING # also causes error when using WHERE
    row_num_alias <= 20

在此查询中，HAVING 子句中对 row_num_alias 字段的引用导致以下错误：Field 'row_num_alias' not found. 替换 [=15= 时出现相同的错误] 带有 WHERE 子句的子句，似乎为 all window 函数抛出此错误。

这是 BigQuery 中的错误吗？还是我的查询有其他错误？

可能相关：

Mysterious error when combining lead function, second window function and column alias
https://code.google.com/p/google-bigquery/issues/detail?id=336&q=window%20alias

一种解决方法是将其转换为子查询并将 WHERE 子句移到子查询之外（见下文），但这看起来很麻烦（希望没有必要）。

SELECT
    object_alias,
    attribute1_alias,
    attribute2_alias,
    score_alias,
    row_num_alias
FROM
    (SELECT
        tn.object AS object_alias,
        tn.attribute1 AS attribute1_alias,
        tn.attribute2 AS attribute2_alias,
        tn.score AS score_alias,
        ROW_NUMBER() OVER (PARTITION BY attribute1_alias, attribute2_alias ORDER BY score_alias DESC) AS row_num_alias
    FROM
        [datasetName.tableName] tn
    )
WHERE
    row_num_alias <= 20

Answer 1

列别名在 WHERE 子句中不起作用，即使在 BigQuery 中也是如此。也不能保证它们在 HAVING 子句中起作用，尽管某些数据库确实支持它。 ORDER BY 中可以使用列别名；我认为标准的这种支持是逐步淘汰 reference-by-number.

的一部分

您知道正确的解决方案，即使用子查询。

顺便说一句，没有 GROUP BY 的 HAVING 子句看起来很别扭。这样的构造经常在 MySQL 中使用，但仅用作 work-around -- MySQL 中的子查询比在其他数据库中产生更多的开销，因为优化器没有那么复杂。

window 函数字段的别名在 HAVING 和 WHERE 子句中使用时导致 "not found" 错误

Alias of window function field causing a "not found" error when used in HAVING and WHERE clauses

sql

alias

window-functions

google-bigquery