How can I query with SQL Server 2017 for nested values in JSON?

Question

I have to extract information from a JSON formatted column with SQL Server. The problem is that it is nested in different objects in an array in an object in an array - and I kind of lose track. In the below code sample I only get as far as the extracting the actions array - and then I'm stuck. I'm not too familiar with this, unfortunately.

I use SQL Server 2017.

{
    "actions":[
        {
            "class":"actions.entries.class",
            "entries":[
                {
                    "class":"actions.entry.class",
                    "id":null,
                    "key":"BirthDay",
                    "performance":{
                        "class":"actions.entry.performance.class",
                        "origin":null,
                        "originUuid":{
                            "class":"java.util.UUID",
                            "UUID":"3d6c5024-754f-477b-87bc-81d8e5ccadcd"
                        },
                        "performanceDateTime":1556012050827,
                        "performerUuid":{
                            "class":"java.util.UUID",
                            "UUID":"2647a005-a3a8-4362-8f2d-ddd188f500e7"
                        },
                        "registrationDateTime":null,
                        "userUuid":null
                    },
                    "type":"O",
                    "value":"\"2000-01-29T10:34:12.000Z\""
                },
                {
                    "class":"actions.entry.class",
                    "id":null,
                    "key":"Gender",
                    "performance":{
                        "class":"actions.entry.performance.class",
                        "origin":null,
                        "originUuid":{
                            "class":"java.util.UUID",
                            "UUID":"3d6c5024-754f-477b-87bc-81d8e5ccadcd"
                        },
                        "performanceDateTime":1556012050827,
                        "performerUuid":{
                            "class":"java.util.UUID",
                            "UUID":"2647a005-a3a8-4362-8f2d-ddd188f500e7"
                        },
                        "registrationDateTime":null,
                        "userUuid":null
                    },
                    "type":"O",
                    "value":"Female"
                }
            ]
        }
    ]
}

So for example I need to find the value to key "Gender" where the value to key "BirthDay" is not null: "Female" in this case. For the sake of clarity I left out other objects in the entries array.

Any help is welcome!

Answer 1

You may try to get your data using OPENJSON() . With this approach you can get key/value pairs from your nested JSON array, even if this array has different key names. What you need is to reference JSON object or array with AS JSON clause.

JSON input:

DECLARE @json nvarchar(max)
SET @json = N'{
    "actions":[
        {
            "class":"actions.entries.class",
            "entries":[
                {
                    "class":"actions.entry.class",
                    "id":null,
                    "key":"BirthDay",
                    "performance":{
                        "class":"actions.entry.performance.class",
                        "origin":null,
                        "originUuid":{
                            "class":"java.util.UUID",
                            "UUID":"3d6c5024-754f-477b-87bc-81d8e5ccadcd"
                        },
                        "performanceDateTime":1556012050827,
                        "performerUuid":{
                            "class":"java.util.UUID",
                            "UUID":"2647a005-a3a8-4362-8f2d-ddd188f500e7"
                        },
                        "registrationDateTime":null,
                        "userUuid":null
                    },
                    "type":"O",
                    "value":"\"2000-01-29T10:34:12.000Z\""
                },
                {
                    "class":"actions.entry.class",
                    "id":null,
                    "key":"Gender",
                    "performance":{
                        "class":"actions.entry.performance.class",
                        "origin":null,
                        "originUuid":{
                            "class":"java.util.UUID",
                            "UUID":"3d6c5024-754f-477b-87bc-81d8e5ccadcd"
                        },
                        "performanceDateTime":1556012050827,
                        "performerUuid":{
                            "class":"java.util.UUID",
                            "UUID":"2647a005-a3a8-4362-8f2d-ddd188f500e7"
                        },
                        "registrationDateTime":null,
                        "userUuid":null
                    },
                    "type":"O",
                    "value":"Female"
                }
            ]
        }
    ]
}'

Get "Gender" and "Birthday":

SELECT
   t1.[value] AS Birthday,
   t2.[value] AS Gender
FROM OPENJSON(@json, '$.actions')
WITH (
   class nvarchar(max) '$.class',
   entries nvarchar(max) '$.entries' AS JSON
) j
CROSS APPLY OPENJSON(j.entries) 
WITH (
   [key] nvarchar(100) '$.key',
   [value] nvarchar(100) '$.value'
) t1
CROSS APPLY OPENJSON(j.entries) 
WITH (
   [key] nvarchar(100) '$.key',
   [value] nvarchar(100) '$.value'
) t2
WHERE 
   t1.[key] = 'Birthday' AND
   t2.[key] = 'Gender'

Output:

Birthday                    Gender
"2000-01-29T10:34:12.000Z"  Female

Get full JSON data:

SELECT
   t1.class,
   t2.id, t2.[key], t2.[type], t2.[value],
   t3.class, t3.origin, t3.performanceDateTime, t3.registrationDateTime, t3.userUuid,
   t4.class1, t4.UUID1,
   t5.class2, t5.UUID2
FROM OPENJSON(@json, '$.actions')
WITH (
   class nvarchar(max) '$.class',
   entries nvarchar(max) '$.entries' AS JSON
) t1
CROSS APPLY OPENJSON(t1.entries) 
WITH (
   class nvarchar(1000) '$.class',
   id nvarchar(100) '$.id',
   [key] nvarchar(100) '$.key',
   [type] nvarchar(100) '$.type',
   [value] nvarchar(100) '$.value',
   performance nvarchar(max) '$.performance' AS JSON
) t2
CROSS APPLY OPENJSON (t2.performance) 
WITH (
   class nvarchar(1000) '$.class',
   origin nvarchar(100) '$.origin',
   performanceDateTime nvarchar(100) '$.performanceDateTime',
   registrationDateTime nvarchar(100) '$.registrationDateTime',
   userUuid nvarchar(100) '$.userUuid',
   originUuid nvarchar(max) '$.originUuid' AS JSON,
   performerUuid nvarchar(max) '$.performerUuid' AS JSON
) t3
CROSS APPLY OPENJSON (t3.originUuid) 
WITH (
   class1 nvarchar(1000) '$.class',
   UUID1 nvarchar(100) '$.UUID'
) t4
CROSS APPLY OPENJSON (t3.originUuid) 
WITH (
   class2 nvarchar(1000) '$.class',
   UUID2 nvarchar(100) '$.UUID'
) t5

Output:

class                   id          key         type    value                       class                               origin  performanceDateTime     registrationDateTime    userUuid    class1          UUID1                                   class2          UUID2
actions.entries.class               BirthDay    O       "2000-01-29T10:34:12.000Z"  actions.entry.performance.class             1556012050827                                               java.util.UUID  3d6c5024-754f-477b-87bc-81d8e5ccadcd    java.util.UUID  3d6c5024-754f-477b-87bc-81d8e5ccadcd
actions.entries.class               Gender      O       Female                      actions.entry.performance.class             1556012050827                                               java.util.UUID  3d6c5024-754f-477b-87bc-81d8e5ccadcd    java.util.UUID  3d6c5024-754f-477b-87bc-81d8e5ccadcd

Update:

If you have JSON data as values in table column, use this approach to get data:

CREATE TABLE #Data (
   JsonData nvarchar(max)
)
INSERT INTO #Data 
   (JsonData)
VALUES 
   (N'{"actions": "value1"}'),
   (N'{"actions": "value2"}')

SELECT *
FROM #Data d
CROSS APPLY OPENJSON(d.JsonData) j

Output:

JsonData                key     value   type
{"actions": "value1"}   actions value1  1
{"actions": "value2"}   actions value2  1

Answer 2

Let me know if this help you.

DECLARE @json nvarchar(max) = N'{
    "actions":[
        {
            "class":"actions.entries.class",
            "entries":[
                {
                    "class":"actions.entry.class",
                    "id":null,
                    "key":"BirthDay",
                    "performance":{
                        "class":"actions.entry.performance.class",
                        "origin":null,
                        "originUuid":{
                            "class":"java.util.UUID",
                            "UUID":"3d6c5024-754f-477b-87bc-81d8e5ccadcd"
                        },
                        "performanceDateTime":1556012050827,
                        "performerUuid":{
                            "class":"java.util.UUID",
                            "UUID":"2647a005-a3a8-4362-8f2d-ddd188f500e7"
                        },
                        "registrationDateTime":null,
                        "userUuid":null
                    },
                    "type":"O",
                    "value":"\"2000-01-29T10:34:12.000Z\""
                },
                {
                    "class":"actions.entry.class",
                    "id":null,
                    "key":"Gender",
                    "performance":{
                        "class":"actions.entry.performance.class",
                        "origin":null,
                        "originUuid":{
                            "class":"java.util.UUID",
                            "UUID":"3d6c5024-754f-477b-87bc-81d8e5ccadcd"
                        },
                        "performanceDateTime":1556012050827,
                        "performerUuid":{
                            "class":"java.util.UUID",
                            "UUID":"2647a005-a3a8-4362-8f2d-ddd188f500e7"
                        },
                        "registrationDateTime":null,
                        "userUuid":null
                    },
                    "type":"O",
                    "value":"Female"
                }
            ]
        }
    ]
}';

SELECT
     [PVT].[action_index]
    ,[CNV].[BirthDay]
    ,[PVT].[Gender]
FROM
(
    SELECT
         [action_index] = [actions].[key]
        ,[entry_field] = [entries].[key]
        ,[entry_value] = [entries].[value]
    FROM OPENJSON(@json, '$.actions') AS [actions] -- iterate over actions array
    OUTER APPLY OPENJSON([actions].[value], '$.entries') -- iterate over entries array for each action
    WITH
    (
         [key] nvarchar(128)
        ,[value] nvarchar(max)
    ) AS [entries]
) AS [SRC]
PIVOT
(
    MAX([entry_value]) FOR [entry_field] IN ([BirthDay], [Gender]) -- pivot the data only for the required fields
) AS [PVT]
CROSS APPLY
(
    SELECT
         [BirthDay] = TRY_CONVERT(datetimeoffset, NULLIF(REPLACE([BirthDay], '"', ''), ''))
) AS [CNV]
WHERE (1 = 1)
    AND ([CNV].[BirthDay] IS NOT NULL);