sql - 在流分析中将列逆透视为两个新列

Question

我有一个来自 IoT 中心的流，例如:

{
    "store_id": "111",
    "data": [
        {
            "timestamp": "2018-04-06T11:46:11.842305",
            "book_id": "001",
            "author_id": "101"
        },
        {
            "timestamp": "2018-04-06T11:46:11.842306",
            "book_id": "002",
            "author_id": "102"
        },
        {
            "timestamp": "2018-04-06T11:46:11.842307",
            "book_id": "003",
            "author_id": "103"
        }
    ]
}

我想在 SQL DB 中传递这个流，如下所示:

id    id_type     timestamp 
001   book_id     2018-04-06T11:46:11.842305  
101   author_id   2018-04-06T11:46:11.842305 
002   book_id     2018-04-06T11:46:11.842306 
102   author_id   2018-04-06T11:46:11.842306 
003   book_id     2018-04-06T11:46:11.842307 
103   author_id   2018-04-06T11:46:11.842307

有没有办法使用交叉应用或其他方式从多json元素创建两个新列

Answer 1

如果它是静态数据透视表(您提前知道字段列表，并且可以对它们的值进行硬编码)，那么您将得到如下结果:

WITH Unfolding AS (
    SELECT
        d.ArrayValue.*
    FROM input i
    CROSS APPLY GetArrayElements(i.data) d
),
Books AS (
    SELECT
        timestamp,
        book_id as id,
        'book' as id_type
    FROM Unfolding
),
Authors AS (
    SELECT
        timestamp,
        author_id as id,
        'author' as id_type
    FROM Unfolding
),
AllRecords AS (
    SELECT timestamp, id, id_type FROM Books
    UNION
    SELECT timestamp, id, id_type FROM Authors
)
SELECT
    *
INTO output
FROM AllRecords

您创建一个CTE最后提取每个实体并将它们全部合并。

如果您有动态值，则需要使用 JavaScript UDF 。遗憾的是我没有代码示例。它应该很简单(但有点痛苦)。