6

Frequently in Javascript you'll have something like

[ 7,2, [6,7], 2,10 ]

How would you query that structure with OPENJSON I would like this,

0, 7
1, 2
2, 6,
2, 7,
3, 2
4, 10

I'm having a hard time conditionally unwrapping that JSON array.

Sample Data

declare @ex nvarchar(max) = '[ 7,2, [6,7], 2,10 ]';

My attempt

Find my query here

SELECT *
FROM OPENJSON(@ex, '$') AS j1

This gets you to,

key value   type
0   7       2
1   2       2
2   [6,7]   4
3   2       2
4   10      2 

If I try to CROSS APPLY OPENJSON(j1."value", '$') AS j2;, I get an error about the 7, the first non-array being an invalid array,

Msg 13609 Level 16 State 4 Line 4

JSON text is not properly formatted. Unexpected character '7' is found at position 0.

How do I use CROSS APPLY OPENJSON to conditionally unwrap the rows that are arrays (type=4) while leaving alone non-arrays (in the above like type=2)? I don't want that [6,7] in there. I want two rows with key=2 that have values 6, and 7 respectively.

10

If you are strictly confident that your nested arrays will never go deeper than N levels, you can completely unwrap the array-of-arrays with N uses of APPLY. If you need to handle for arbitrary nesting levels, you can unwrap the array-of-arrays recursively using something like the following, which will produce output similar to the following


|----|-------|---------|-----|-------|------|
| id | level | path    | key | value | type |
|----|-------|---------|-----|-------|------|
| 1  | 1     | /0      | 0   | 7     | 2    |
| 1  | 1     | /1      | 1   | 2     | 2    |
| 1  | 2     | /2/0    | 0   | 6     | 2    |
| 1  | 2     | /2/1    | 1   | 7     | 2    |
| 1  | 1     | /3      | 3   | 2     | 2    |
| 1  | 1     | /4      | 4   | 10    | 2    |
|----|-------|---------|-----|-------|------|

DB Fiddle

declare @ex table ( 
    i int identity primary key,
    r nvarchar(max) 
); 
insert @ex (r) 
values ('[ 7,2, [6,7], 2, 10 ]')
      ,('[ 7,2, [6,7], 2, 10 , [6,[7,8]]]')
;

with j as (
    select 
        x.i as id,
        convert(int,1) as [level],
        convert(nvarchar(max),N'/')+convert(nvarchar(max),a.[key]) as [path],
        a.[key], 
        a.[value],
        a.[type]
    from @ex x 
    cross apply openjson(x.r) a
    union all 
    select 
        j. id,
        j.[level] + 1,
        j.[path] + convert(nvarchar(max),N'/')+convert(nvarchar(max),a.[key]),
        a.[key], 
        a.[value],
        a.[type]
    from j
    cross apply openjson(j.value) a
    where j.type in (4,5)
       and j.level < 50 --maxrecursion
)
select *
from j
where type not in (4,5)
order by id, [path];

Testing against the 2-level deep nested array from the above example produces the following:


|----|-------|---------|-----|-------|------|
| id | level | path    | key | value | type |
|----|-------|---------|-----|-------|------|
| 2  | 1     | /0      | 0   | 7     | 2    |
| 2  | 1     | /1      | 1   | 2     | 2    |
| 2  | 2     | /2/0    | 0   | 6     | 2    |
| 2  | 2     | /2/1    | 1   | 7     | 2    |
| 2  | 1     | /3      | 3   | 2     | 2    |
| 2  | 1     | /4      | 4   | 10    | 2    |
| 2  | 2     | /5/0    | 0   | 6     | 2    |
| 2  | 3     | /5/1/0  | 0   | 7     | 2    |
| 2  | 3     | /5/1/1  | 1   | 8     | 2    |
|----|-------|---------|-----|-------|------|

See this question also for related material.

6
declare @ex nvarchar(max) = '[ 7,2, [6,7], 2, 10 ]';


;WITH cte
AS (
    SELECT *
    FROM OPENJSON(@ex, '$') AS j1
)
SELECT c.[key], ISNULL(v.value, c.value)
FROM cte c
    OUTER APPLY (
        SELECT *
        FROM OPENJSON(c.value, '$') AS j1
        WHERE c.[type] = 4

    )v
;

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.