WITH recCTE AS
(
SELECT ID
,NestLevel = 0
,ObjectIndex = CAST(1 AS bigint)
,SortString = CAST(N'0' N'sort' COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,JsonPath = CAST(N'$' COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,JsonKey = CAST(N'$' COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,JsonValue = CAST(AnyJSON COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,JsonType = CAST(CASE WHEN LEFT(TRIM(AnyJSON),1)=N'[' THEN 4 ELSE 0 END AS TINYINT)
,NestedJSON = CAST(CASE WHEN ISJSON(AnyJSON)=1
THEN AnyJSON
ELSE NULL END COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
FROM @table t
UNION ALL
SELECT r.ID
,r.NestLevel+1
,ROW_NUMBER() OVER(ORDER BY (SELECT NULL))
,CAST(CONCAT(r.SortString,REPLACE(STR(ROW_NUMBER() OVER(ORDER BY (SELECT NULL)),5),' ','0')) COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,CAST(CONCAT(r.JsonPath, CASE WHEN r.JsonType=4 --<-- see the docs for OPENJSON()
THEN CONCAT('[',A.[key],']')
ELSE '.' + A.[key] END) COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,CAST(A.[key] COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,CAST(r.JsonValue COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
,A.[type]
,CAST(A.[value] COLLATE DATABASE_DEFAULT AS NVARCHAR(MAX))
FROM recCTE r
CROSS APPLY OPENJSON(r.NestedJSON) A
WHERE ISJSON(r.NestedJSON)=1
)
SELECT ID
,NestLevel
,ObjectIndex
,JsonPath
,JsonKey
,NestedJSON AS JsonValue
,SortString --<-- just to illustrate the sorting, not needed in the output
FROM recCTE
WHERE ISJSON(NestedJSON)=0
ORDER BY ID,SortString;