Parse JSON file - Improve query in SQL Server - sql-server

Question

From this JSON File (just an example) I need to reach this final result
{
"Id": "101",
"name": "C01",
"testparameters": {
"room": [
{
"Floor": "First_Floor",
"Rooms": ["Room1", "Room2", "Room3"]
},
{
"Floor": "Second_Floor",
"Rooms": ["Room1", "Room2", "Room3"]
}
],
"area": [
{
"Name": "Area1",
"Subarea": ["Subarea1", "Subarea2", "Subarea3"]
},
{
"Name": "Area2",
"Subarea": ["Subarea4", "Subarea5"]
}
],
"requirements": [{
"condition": "",
"type": "type1",
"field1": "",
"field2": "aaaaa",
"operator": "",
"value2": ""
},
{
"condition": "AND",
"type": "type2",
"field1": "",
"field2": "numPersons",
"operator": ">",
"value2": "20"
},
{
"condition": "OR",
"type": "type2",
"field1": "",
"field2": "specification",
"operator": "=",
"value2": "wifi"
}
]
}
}
'
In one register I need to have all the information that is requested.
This is the first time that I need to parse a JSON file. After asking (a lot) I manage to reach the expected result by doing this:
Parsing JSON Example
However, I had to open the JSON file several times, and process each section apart. I'm wondering, how can I improve the code by reducing the number of times that I need to use the OPENJSON function, and in particular, how to rewrite the code snippet that handle the requirements section.

Answer 1

I must say, your desired result looks pretty de-normalized, you may want to rethink it.
Be that as it may, you can combine these quite easily, by using nested subqueries
SELECT
ID = JSON_VALUE(j.json, '$.Id'),
name = JSON_VALUE(j.json, '$.name'),
area = (
SELECT STRING_AGG(concat(d.a , ':', b.value),' - ')
from openjson(j.json, '$.testparameters.area')
with
(
a nvarchar(250) '$.Name',
s nvarchar(max) '$.Subarea' as json
) as d
cross apply openjson(d.s) as b
),
room = (
SELECT STRING_AGG(concat(c.f, ':', d.value), ' - ')
from openjson(j.json, '$.testparameters.room')
with(
f nvarchar(50) '$.Floor',
r nvarchar(Max) '$.Rooms' as json
) as c
cross apply openjson(c.r) as d
),
requirements = (
SELECT IIF(
SUBSTRING(requirements,1,3) = 'AND' or SUBSTRING(requirements,1,3) = 'OR',
SUBSTRING(requirements,5,LEN(requirements)),
requirements
)
from
(
select
STRING_AGG(CONCAT_WS(' ',
a.condition,
a.field2,
operator,
IIF (ISNUMERIC(a.value2) = 1,
a.value2,
CONCAT('''',a.value2,'''')
)
),
' ') as requirements
from openjson(j.json, '$.testparameters.requirements' )
with
(
condition nvarchar(255) '$.condition',
type nvarchar(255) '$.type',
field2 nvarchar(255) '$.field2',
operator nvarchar(255) '$.operator',
value2 nvarchar(255) '$.value2'
) a
where a.type = 'type2'
) a
)
FROM (VALUES(#json)) AS j(json) -- or you can reference a table