Parse JSON document into table - json

Question

I'm working on parsing JSON document with an object array into a SQL Server table. I'm stuck with how to parse the complex object array.
I tried subproject.id and that did not work. I usually use the below code to parse a JSON array which works just fine but in this case it does not.
JSON:
{
"Data": [
{
"name": "ABC",
"date": "2020-01-20",
"subproject": [
{
"id": "123",
"projectname": "new1",
"refnum": "123:new1"
},
{
"id": "456",
"projectname": "new2",
"refnum": "456:new2"
}
],
"projectid": "1234",
"projectdate": "2020-01-27"
},
{
"name": "DEF",
"date": "2020-01-30",
"subproject": [
{
"id": "789",
"projectname": "new3",
"refnum": "789:new3"
},
{
"id": "901",
"projectname": "new4",
"refnum": "901:new4"
}
],
"projectid": "4567",
"projectdate": "2020-02-07"
}
]
}
SQL:
DECLARE #JSON VARCHAR(MAX)
SELECT #JSON = BulkColumn
FROM OPENROWSET (BULK 'c:/data/project.json', SINGLE_CLOB) X
SELECT *
FROM OPENJSON (#JSON)
WITH (
[name] NVARCHAR(256),
[date] DATE,
[projectid] INT,
[projectdate] DATE
)

Answer 1

You need to use AS JSON clause in the first OPENJSON() call (to specify that the $.subproject property contains an inner JSON array) and a combination of another OPENJSON() call and APPLY operator:
SELECT *
FROM OPENJSON (#JSON, '$.Data') WITH (
[name] NVARCHAR(256),
[date] DATE,
[projectid] INT,
[projectdate] DATE,
[subproject] NVARCHAR(MAX) '$.subproject' AS JSON
) j1
OUTER APPLY OPENJSON (j1.[subproject]) WITH (
[subprojectid] INT '$.id',
[subprojectname] NVARCHAR(256) '$.projectname',
[subprojectrefnum] NVARCHAR(256) '$.refnum'
) j2