如何在 SQL Server 中展平来自 JSON 的嵌套数组

Question

我正在尝试使用下面的代码在 SQL Server 中展平来自 JSON 的嵌套数组，但没有成功。

使用的 JSON

'{
    "shipmentDetails": {
        "shipmentId": "JHVJD5627278788"
    },
    "shipmentStops": [
        {
            "stopSequence": 1,
            "orderReferenceNumbers": [
                "2120549020", "test"
            ]
        },
        {
            "stopSequence": 2,
            "orderReferenceNumbers": [
                "2120549020", "2120549002"
            ]
        }
    ]
}'

DECLARE @Step AS NVARCHAR(max) = N'Variables declaration';
DECLARE @JSON1 AS NVARCHAR(MAX);

SET @JSON1 = '{
    "shipmentDetails": {
        "shipmentId": "JHVJD5627278788"
    },
    "shipmentStops": [
        {
            "stopSequence": 1,
            "orderReferenceNumbers": [
                "2120549020", "test"
            ]
        },
        {
            "stopSequence": 2,
            "orderReferenceNumbers": [
                "2120549020", "2120549002"
            ]
        }
    ]
}'

IF OBJECT_ID('JSONPO2') IS NOT NULL
    DROP TABLE JSONPO2

SET @Step = N'JSON data parsing and loading into JSONPO2 temp table'

SELECT DISTINCT ShipDetails.shipmentId AS shipmentId
    ,ShipmentStops.stopSequence AS stopSequence
    ,ShipmentStops.orderReferenceNumbers AS orderReferenceNumbers
INTO JSONPO2
FROM OPENJSON(@JSON1) WITH (
        shipmentDetails NVARCHAR(MAX) AS JSON
        ,shipmentStops NVARCHAR(MAX) AS JSON
        ) AS [Data]
CROSS APPLY OPENJSON(shipmentDetails) WITH (shipmentId NVARCHAR(20)) AS ShipDetails
CROSS APPLY OPENJSON(shipmentStops) WITH (
        stopSequence INT
        ,orderReferenceNumbers NVARCHAR(MAX) AS JSON
        ) AS ShipmentStops
CROSS APPLY OPENJSON(orderReferenceNumbers) WITH (orderReferenceNumbers VARCHAR(max)) 
AS orderReferenceNumbers

SELECT *
FROM JSONPO2

从上面的代码中，我只收到两行带有一个奇怪的数组

shipmentId	stopSequence	orderReferenceNumbers
JHVJD5627278788	1	[ "2120549020", "test" ]
JHVJD5627278788	2	[ "2120549020", "2120549002" ]

如何更改代码以解析嵌套数组并有如下四行？

shipmentId	stopSequence	orderReferenceNumbers
JHVJD5627278788	1	2120549020
JHVJD5627278788	1	test
JHVJD5627278788	2	2120549020
JHVJD5627278788	2	2120549002

感谢任何帮助:)

Answer 1

您的问题是在尝试使用 WITH 子句扩展数组时：

CROSS APPLY OPENJSON(orderReferenceNumbers) 
   WITH (orderReferenceNumbers VARCHAR(max)) AS orderReferenceNumbers

您打开的 JSON 没有属性“orderReferenceNumbers”，它只是：

[“2120549020”，“测试”]

所以这是返回NULL。如果您选择 orderReferenceNumbers.orderReferenceNumbers 而不是 ShipmentStops.orderReferenceNumbers，您会在选择中看到它。

如果您打开一个简单的原始类型 JSON 数组，则不需要使用 WITH。以下查询将返回您之后的输出：

DECLARE @JSON1 AS NVARCHAR(MAX) = N'{
    "shipmentDetails": {
        "shipmentId": "JHVJD5627278788"
    },
    "shipmentStops": [
        {
            "stopSequence": 1,
            "orderReferenceNumbers": [
                "2120549020", "test"
            ]
        },
        {
            "stopSequence": 2,
            "orderReferenceNumbers": [
                "2120549020", "2120549002"
            ]
        }
    ]
}';

SELECT  sd.shipmentId, 
        ss.stopSequence, 
        orderReferenceNumber = orn.Value
FROM    OPENJSON(@JSON1)
            WITH(shipmentDetails NVARCHAR(MAX) AS JSON, shipmentStops NVARCHAR(MAX) AS JSON) AS d
        CROSS APPLY OPENJSON(d.shipmentDetails)
            WITH(shipmentId NVARCHAR(20)) AS sd
        CROSS APPLY OPENJSON(d.shipmentStops)
            WITH(stopSequence INT, orderReferenceNumbers NVARCHAR(MAX) AS JSON) AS ss
        CROSS APPLY OPENJSON(orderReferenceNumbers) AS orn;

Example on db<>fiddle

顺便说一句，如果您在 JSON 中只有一个 shipmentId（这是有意义的，否则您最终会得到交叉连接），您可以稍微简化一下，并删除其中一个 OPENJSON()s：

SELECT  d.shipmentId, 
        ss.stopSequence, 
        orderReferenceNumber = orn.Value
FROM    OPENJSON(@JSON1)
            WITH(ShipmentId NVARCHAR(20) '$.shipmentDetails.shipmentId', 
                shipmentStops NVARCHAR(MAX) AS JSON) AS d
        CROSS APPLY OPENJSON(d.shipmentStops)
            WITH(stopSequence INT, orderReferenceNumbers NVARCHAR(MAX) AS JSON) AS ss
        CROSS APPLY OPENJSON(ss.orderReferenceNumbers) AS orn;