Format JSON as nested arrays based on id in SQL

Question

I have a stored procedure in SQLS erver that gives the output in the following JSON format:

[
   {
  "accountid":"12312312",
  "Id":1,
  "name":"Ace Signs Ltd"
   },
   {
  "accountid":"213123123",
  "Id":2,
  "name":"Workshare Technology"
   },
  {
  "accountid":"12312312",
  "Id":1,
  "name":"Ace Signs Ltd"
  },
  {
  "accountid":"123123123",
  "Id":2,
  "name":"Workshare"
   }
]

But I want them grouped into nested arrays based on the ID as shown below. Where the ones with the same ID are one tuple.

   {
   "match":[
      [
        {
        "accountid":"12312312",
        "Id":1,
        "name":"Ace Signs Ltd"
        },
        {
        "accountid":"12312312",
        "Id":1,
        "name":"Ace Signs Ltd"
        }
      ],
      [
        {
        "accountid":"12312312",
        "Id":2,
        "name":"Workshare Technology"
        },
        {
        "accountid":"213123123",
        "Id":2,
        "name":"Workshare"
        }
       ]
      ]
    }

The part of the stored procedure that generates the JSON is as follows:

SELECT *
FROM TestJsonFormat 
FOR JSON AUTO

Sample data:

CREATE TABLE TestJsonFormat (
    accountid varchar(255), 
    Id int,
    name varchar(255)
)

insert into TestJsonFormat values(12312312,1,'Ace Signs Ltd')
insert into TestJsonFormat values(213123123,2,'Workshare Technology')
insert into TestJsonFormat values(12312312,1,'Ace Signs Ltd')
insert into TestJsonFormat values(123123123,2,'Workshare')

Answer 1

One possible approach to generate the expected JSON output is a combination from FOR JSON AUTO and basic string aggregation. The following example demostrates this:

Table:

CREATE TABLE TestJsonFormat (
    accountid varchar(255), 
    Id int,
    name varchar(255)
)
insert into TestJsonFormat values(12312312,1,'Ace Signs Ltd')
insert into TestJsonFormat values(213123123,2,'Workshare Technology')
insert into TestJsonFormat values(12312312,1,'Ace Signs Ltd')
insert into TestJsonFormat values(123123123,2,'Workshare')

Statement:

SELECT CONCAT('{"match": [', STRING_AGG(json, ','), ']}')
FROM (
   SELECT DiSTINCT t.id, j.json
   FROM TestJsonFormat t
   CROSS APPLY (
      SELECT accountId, id, name
      FROM TestJsonFormat 
      WHERE id = t.id
      FOR JSON AUTO
   ) j (json)
) cte

Result (formatted):

{
  "match": [
    [
      {
        "accountId":"12312312",
        "id":1,
        "name":"Ace Signs Ltd"
      },
      {
        "accountId":"12312312",
        "id":1,
        "name":"Ace Signs Ltd"
      }
    ],
    [
      {
        "accountId":"213123123",
        "id":2,
        "name":"Workshare Technology"
      },
      {
        "accountId":"123123123",
        "id":2,
        "name":"Workshare"
      }
    ]
  ]
}