Get Nested JSON from SQL table - sql

Question

Below is my table data looks like.
Below is SQL Query for Create table
CREATE TABLE [dbo].[CategoryMaster](
[CategoryId] [int] NOT NULL,
[ParentId] [int] NULL,
[Name] [varchar](50) NULL,
CONSTRAINT [PK_CategoryMaster] PRIMARY KEY CLUSTERED
(
[CategoryId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (1, NULL, N'Toys & Games')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (2, 1, N'Art And Crafts')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (3, 1, N'Baby & Toddler Toys')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (4, 1, N'Bikes, Trikes & Ride-Ons')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (5, 2, N'Aprons & Smocks')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (6, 2, N'Blackboards & Whiteboards')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (7, 2, N'Clay & Dough')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (8, 1, N'Pretend Play')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (9, 8, N'Kitchen Toys')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (10, 9, N'Cooking Appliances')
GO
INSERT [dbo].[CategoryMaster] ([CategoryId], [ParentId], [Name]) VALUES (11, 9, N'Cookware')
GO
ALTER TABLE [dbo].[CategoryMaster] WITH CHECK ADD CONSTRAINT [FK_CategoryMaster_CategoryMaster] FOREIGN KEY([ParentId])
REFERENCES [dbo].[CategoryMaster] ([CategoryId])
GO
ALTER TABLE [dbo].[CategoryMaster] CHECK CONSTRAINT [FK_CategoryMaster_CategoryMaster]
GO
I had tried many queries but not able to get desired result. can anyone please help me out from this situation?
I want output like below.

Answer 1

You can create a recursive function like below:
CREATE FUNCTION Create_Json(#CategoryId INT, #IsRoot INT)
RETURNS VARCHAR(MAX)
BEGIN
DECLARE #Json NVARCHAR(MAX) = '{}', #Name NVARCHAR(MAX), #Children NVARCHAR(MAX)
SET #Json = (SELECT P.[Name],JSON_QUERY(dbo.Create_Json(P.CategoryId, 2) ) AS Children
FROM [dbo].[CategoryMaster] AS P
WHERE P.ParentId = #CategoryId
FOR JSON AUTO);
IF(#IsRoot = 1)
BEGIN
SELECT #Name = P.[Name] FROM [dbo].[CategoryMaster] AS P WHERE P.CategoryId = #CategoryId
SET #Json = '"result": {"Name":"' + #Name + '","Children":' + CAST(#Json AS NVARCHAR(MAX)) + '}'
SET #IsRoot = 0
END
RETURN #Json
END
and call it like:
select dbo.Create_Json(1, 1)
Please find the db<>fiddle here.