SQL Select to JSON for Menu Structure

Question

I was looking for help with a query which will produce the output in JSON that I could use to populate a Menu, thus the JSON needs to create the menu structure.

Here are the two tables that I have, and the best query I've been able to write (which does not produce the output I need) is:

SELECT 
    c.ID As CategoryID, 
    c.Name As CategoryName,
    p.ProductName as ProductName
    p.ProductID as ProductID
FROM Category c, Product p
WHERE 
    c.ID = p.CategoryID
FOR JSON PATH, ROOT('Menu')

Table: Category

ID   |  Name
---------------
1    |  Fruit
2    |  Vegetable

Table: Product

ProductID  |   CategoryID  |  ProductName
----------------------------------------
1           |  1           |  Apple
2           |  1           |  Orange
3           |  2           |  Celery
4           |  2           |  Carrot
5           |  1           |  Banana

The desired output for this query would be the following

   menu: 
      [
         {name: 'Fruit', ID: '1', Items: 
            [
               {productname: 'Apple', productid: '1'},
               {productname: 'Orange', productid: '2'},
               {productname: 'Banana', productid: '5'}
            ]
         },
         {name: 'Vegetable', ID: '2', Items: 
            [
               {productname: 'Celery', productid: '3'},
               {productname: 'Carrot', productid: '4'}
            ]
         }
   ]

Is anyone able to explain the steps in which I could change my query to achieve this?

Answer 1

You may choose between the following options:

• FOR JSON AUTO and an appropriate join. The output is automatically generated based on the structure of the SELECT statement.
• A combination of two nested FOR JSON AUTO statements:

Table:

CREATE TABLE Category (ID int, Name varchar(50))
INSERT INTO Category (ID, Name)
VALUES
   (1, 'Fruit'),
   (2, 'Vegetable')
CREATE TABLE Product (ProductID int, CategoryID int, ProductName varchar(50))
INSERT INTO Product (ProductID, CategoryID, ProductName)
VALUES
   (1, 1, 'Apple'),
   (2, 1, 'Orange'),
   (3, 2, 'Celery'),
   (4, 2, 'Carrot'),
   (5, 1, 'Banana')

Statement (using FOR JSON AUTO and an appropriate join and SELECT structure):

SELECT 
   c.Name AS name, c.ID as id, 
   items.ProductName AS productname, items.ProductId AS productid
FROM Category c
JOIN Product items ON (c.ID = items.CategoryId)
ORDER BY c.ID, items.ProductId
FOR JSON AUTO, ROOT ('menu')

Statement (using two FOR JSON AUTO statements):

SELECT 
   c.Name AS name, c.ID as id, 
   items = (
      SELECT p.ProductName AS productname, p.ProductID AS productid
      FROM Product p
      WHERE p.CategoryID = c.ID
      FOR JSON AUTO
   )
FROM Category c
FOR JSON AUTO, ROOT ('menu')

Result:

{
  "menu":[
    {
      "name":"Fruit",
      "id":1,
      "items":[
        {"productname":"Apple","productid":1},
        {"productname":"Orange","productid":2},
        {"productname":"Banana","productid":5}
      ]
    },
    {
      "name":"Vegetable",
      "id":2,
      "items":[
        {"productname":"Celery","productid":3},
        {"productname":"Carrot","productid":4}
      ]
    }
  ]
}

Answer 2

Try this:

DECLARE @Category TABLE
(
    [ID] TINYINT
   ,[Name] VARCHAR(12)
);

INSERT INTO @Category ([ID], [Name])
VALUES (1, 'Fruit')
      ,(2, 'Vegetable');

DECLARE @Product TABLE
(
    [ProductID] TINYINT
   ,[CategoryID] TINYINT
   ,[ProductName] VARCHAR(12)
);

INSERT INTO @Product ([ProductID], [CategoryID], [ProductName])
VALUES (1, 1, 'Apple')
      ,(2, 1, 'Orange')
      ,(3, 2, 'Celery')
      ,(4, 2, 'Carrot')
      ,(5, 1, 'Banana');


SELECT 
    c.ID As CategoryID, 
    c.Name As CategoryName,
    Items.ProductName as ProductName,
    Items.ProductID as ProductID
FROM @Category c
INNER JOIN @Product Items
ON
    c.ID = Items.CategoryID
FOR JSON AUTO, ROOT('Menu')