Extract values from JSON of Array in T-SQL - arrays

Question

I have a JSON like this to process in SQL
{"RowIndex":[1,2], "Data":["a","b"]}
and i want to extract the data to show that as a table like this
RowIndex Data
1 a
2 b
I understand that i have to use OPENJSON, JSON_QUERY or JSON_VALUE but i cannot find a way to get what I want that not implies to write a query with many join like
select C1.value as RowIndex,
C2.value as Data,
From (select [key], value from OPENJSON(JSON_QUERY(#jsonstring, '$.RowIndex'))) C1
inner join (select [key], value from OPENJSON(JSON_QUERY(#jsonstring, '$.Data'))) C2 on C1.[key] = C2.[key]
Because if the arrays in the JSON grow the query will be unmaintenable and slow

Answer 1

One method, using a "couple" of OPENJSON clauses:
DECLARE #JSON nvarchar(MAX) = N'{"RowIndex":[1,2], "Data":["a","b"]}';
SELECT RI.[value] AS RowIndex,
D.[value] AS Data
FROM OPENJSON(#JSON)
WITH (RowIndex nvarchar(MAX) AS JSON,
Data nvarchar(MAX) AS JSON) J
CROSS APPLY OPENJSON(RowIndex) RI
CROSS APPLY OPENJSON(Data) D
WHERE RI.[key] = D.[key];
To elaborate on my comments though, it seems like you should be fixing the JSON design and have something like this:
[
{
"RowIndex": "1",
"Data": "a",
"Number": "1"
},
{
"RowIndex": "2",
"Data": "b",
"Number": "3"
}
]
Which can be far more easily queried:
DECLARE #JSON nvarchar(MAX) = N'[
{
"RowIndex": "1",
"Data": "a",
"Number": "1"
},
{
"RowIndex": "2",
"Data": "b",
"Number": "3"
}
]';
SELECT *
FROM OPENJSON(#JSON)
WITH (RowIndex int,
Data char(1),
Number int) OJ;