Parse JSON structure in SQL - sql

Question

I have written a code that reads information from JSON lines to table in SQL:
declare #pJSON varchar(max) = '
{
"School": "MiddleSchool",
"Password": "SchoolPassword",
"Attributes": [
{
"Type": "Exam",
"Value": "1"
},
{
"Type": "Class",
"Value": "11b"
},
{
"Type": "Math",
"Value": [
{
"ExamDate": "2019-01-01",
"Points": 100,
"Grade": 10,
"Notes": "Good"
}
]
}
]
} '
select ExamDate, Points, Grade, Notes
from OPENJSON(#pJSON, N'$.Attributes[2].Value')
cross apply openjson ([Value])
with
(
ExamDate date,
Points int,
Grade int,
Notes varchar(max)
) as [value]
Code works fine, but I really hate N'$.Attributes[2].Value' part. Exam information can be in the first, second, third place, so [2] doesn't really work for me. Do you have any suggestions for me, how I can improve this code? Thank you!

Answer 1

You could use JSON_QUERY:
select ExamDate, Points, Grade, Notes
from OPENJSON(JSON_QUERY(#pJSON, N'$.Attributes'))
with
(
ExamDate date N'$.Value[0].ExamDate', -- here 0 because Value is array too
Points int N'$.Value[0].Points',
Grade int N'$.Value[0].Grade',
Notes varchar(max) N'$.Value[0].Notes'
) as [value]
WHERE ExamDate IS NOT NULL;
db<>fiddle demo
EDIT:
In original question there was only one exam in array. If array could contain more than code should be adjusted:
SELECT s2.[key]
,ExamValue = JSON_VALUE(s2.value, '$.ExamDate')
,Points = JSON_VALUE(s2.value, '$.Points')
,Grade = JSON_VALUE(s2.value, '$.Grade')
,Notes = JSON_VALUE(s2.value, '$.Notes')
FROM OPENJSON(JSON_QUERY(#pJSON, N'$.Attributes')) s
CROSS APPLY OPENJSON(JSON_QUERY(s.value, N'$.Value')) s2;
-- or
SELECT [value].*
FROM OPENJSON(JSON_QUERY(#pJSON, N'$.Attributes'))
CROSS APPLY OPENJSON(JSON_QUERY(value, N'$.Value'))
with
(
ExamDate date N'$.ExamDate',
Points int N'$.Points',
Grade int N'$.Grade',
Notes varchar(max) N'$.Notes'
) as [value];
db<>fiddle demo