Select last value from Json array

Question

I need to get the last item in an array from a JSON format. I have this JSON.

  @json =   
  N\'{ 
        \"solution\": \"xxxxxxxxxxxxxxxxxxxxx\",
        \"opt         


        

Answer 1

First, your JSON string is malformed. You need to remove the comma after the closing array bracket.

So let's declare our variable:

DECLARE @json NVARCHAR(MAX) = N'{ 
        "solution": "xxxxxxxxxxxxxxxxxxxxx",
        "options": [
            {
                "choice_id": 205073,
                "choice": "aaaa"
            },
            {
                "choice_id": 205074,
                "choice": "bbbb"
            },
            {
                "choice_id": 205075,
                "choice": "cccc"
            },
            {
                "choice_id": 205076,
                "choice": "ffffdd"
            }
        ]
    }'

Now you can use a combination of OPENJSON() and FOR JSON to get the last record in the array.

SELECT jsonfield = CAST((
                            SELECT TOP 1
                                j.solution
                                ,o.choice_id
                                ,o.choice
                            FROM
                                OPENJSON(@json)
                                WITH
                                (
                                    solution VARCHAR(MAX) '$.solution'
                                    ,options NVARCHAR(MAX) '$.options' AS JSON
                                ) j
                            CROSS APPLY
                                OPENJSON(options)
                                WITH
                                (
                                    choice_id INT '$.choice_id'
                                    ,choice VARCHAR(4) '$.choice'
                                ) o
                            ORDER BY o.choice_id DESC
                            FOR JSON PATH, WITHOUT_ARRAY_WRAPPER
                        ) AS NVARCHAR(MAX))

EDIT:

Or you can use this query, if you don't want to order by any of the node values:

SELECT jsonfield = CAST((
                            SELECT TOP 1
                                j.solution
                                --,o.*
                                ,c.choice_id
                                ,c.choice
                            FROM OPENJSON(@json)
                            WITH
                                (
                                    solution VARCHAR(MAX) '$.solution'
                                    ,options NVARCHAR(MAX) '$.options' AS JSON
                                ) j
                            CROSS APPLY OPENJSON(options) o
                            CROSS APPLY OPENJSON(o.Value) 
                            WITH (
                                    choice_id int '$.choice_id',
                                    choice varchar(4) '$.choice'
                                    ) c
                            ORDER BY [key] DESC
                            FOR JSON PATH, WITHOUT_ARRAY_WRAPPER
                        ) AS NVARCHAR(MAX))