MSSQL Query JSON displays Null value - sql

Question

I have a table PublicRelations with a column called Students in a SQL Server database called Subjects.
[
{ "Label": "Name", "ColumnValue": "Trudie" },
{ "Label": "Class", "ColumnValue": "PublicRelations" },
{ "Label": "Room", "ColumnValue": "8049" },
{ "Label": "HttpPath", "ColumnValue": "https://www.google.com/" }
]
I only get NULL when I run the below query using the Json_value. I'd like to get it to display the value from the array. I believe this may have to do with the 4000 character limit?
SELECT [StuduentID],
[Students],
--JSON_VALUE([Students],'$.ColumnValue') AS Name --Only returns NULL
FROM [Subjects].[dbo].[PublicRelations] c
CROSS APPLY OPENJSON(c.Students)
WITH ( Name int '$.Name',
Value nvarchar(255) '$.ColmunValue'
) AS jsonValues
WHERE jsonValues.ColumnValue = 'Trudie'
The query works and I can find what I need, but again, I only get NULL when I want to display that part of the JSON column in my results.

Answer 1

The statement is wrong and you has the following issues (as #MartinSmith already mentioned):
Syntax error - '$.ColmunValue' should be '$.ColumnValue'.
Wrong schema definition (the WITH clause) - I can't see Name key in the input JSON.
Wrong use of JSON_VALUE() - this function extracts scalar value from a JSON string, so JSON_VALUE([Students],'$.ColumnValue') returns NULL with this JSON input in lax mode.
You may try with the following statement (based on the statement in the question):
Table:
CREATE TABLE PublicRelations (
StudentID int,
Students nvarchar(1000))
INSERT INTO PublicRelations (StudentID, Students)
VALUES (1, N'[
{ "Label": "Name", "ColumnValue": "Trudie" },
{ "Label": "Class", "ColumnValue": "PublicRelations" },
{ "Label": "Room", "ColumnValue": "8049" },
{ "Label": "HttpPath", "ColumnValue": "https://www.google.com/" }
]')
Statement:
SELECT p.StudentID, j.*
FROM [PublicRelations] p
CROSS APPLY OPENJSON(p.Students) WITH (
Name nvarchar(50) '$.Label',
Value nvarchar(255) '$.ColumnValue'
) j
WHERE EXISTS (
SELECT 1
FROM OPENJSON(p.Students) WITH (Value nvarchar(255) '$.ColumnValue')
WHERE Value = N'Trudie'
) AND (j.Name IN ('Name', 'Class', 'Room'))
Result:
StudentID Name Value
1 Name Trudie
1 Class PublicRelations
1 Room 8049