Mysql concat and group_concat - mysql

Question

I'm trying to come up with a sql query that shows the client information as well as their orders.
this is the desired result:
{
"success": true,
"client": {
"name": "General Kenobit",
"email": "test#test.com",
"contact": 123456789,
"registerDate": "2022-04-06T16:00:05.000Z",
"status": "activo",
"orders": [
{
"orderId": 1002,
"total": 19.5,
"payment": "money",
"products": [
{
"productId": 1,
"product": "Test",
"quantity": 4
}
]
},
{
"orderId": 1006,
"total": 67.5,
"payment": "money",
"products": [
{
"productId": 1,
"product": "Test",
"quantity": 4
}
{
"productId": 2,
"product": "Product 2",
"quantity": 3
}
]
},
{
"orderId": 1009,
"total": 134,
"payment": "card",
"products": [
{
"productId": 1,
"product": "Test",
"quantity": 4
}
{
"productId": 2,
"product": "Product 2",
"quantity": 4
}
{
"productId": 3,
"product": "Food",
"quantity": 5
},
]
}
]
}
}
and this is is query I'm trying to solve
SELECT c.name, c.email, c.contact, c.registerDate, c.status,
CONCAT('[',
GROUP_CONCAT(JSON_OBJECT("orderId", o.orderId, "total", o.total, "payment", o.payment, "products",
CONCAT('[', GROUP_CONCAT(JSON_OBJECT("productId", p.productId, "product", p.product, "quantity", op.quantity) SEPARATOR ','), ']')
) SEPARATOR ','),
']') AS 'orders'
FROM t_client AS c
INNER JOIN t_order AS o ON o.email = c.email
INNER JOIN t_orderproduct AS op ON op.orderId = o.orderId
INNER JOIN t_product AS p ON p.productId = op.productId
WHERE c.clientId = 1
GROUP BY c.clientId
If I use the group_concat function before the second json_object I get error #1111 for invalid use of grouping function (group)...
Otherwise this is what it comes back as result:
{
"success": true,
"client": {
"name": "General Kenobit",
"email": "teste#teste.com",
"contact": 123456789,
"registerDate": "2022-04-06T16:00:05.000Z",
"status": "activo",
"orders": [
{
"orderId": 1002,
"total": 19.5,
"payment": "money",
"products": [
{
"productId": 1,
"product": "Test",
"quantity": 4
}
]
},
{
"orderId": 1006,
"total": 67.5,
"payment": "money",
"products": [
{
"productId": 1,
"product": "Test",
"quantity": 4
}
]
},
{
"orderId": 1009,
"total": 134,
"payment": "card",
"products": [
{
"productId": 1,
"product": "Test",
"quantity": 4
}
]
},
{
"orderId": 1006,
"total": 67.5,
"payment": "money",
"products": [
{
"productId": 2,
"product": "Product 2",
"quantity": 3
}
]
},
{
"orderId": 1009,
"total": 134,
"payment": "card",
"products": [
{
"productId": 2,
"product": "Product 2",
"quantity": 4
}
]
},
{
"orderId": 1009,
"total": 134,
"payment": "card",
"products": [
{
"productId": 3,
"product": "Food",
"quantity": 5
}
]
}
]
}
}
I turned the whole query upside down already and don't know where else to tweak.
Any suggestion or tip is appreciated.

Answer 1

You can't have nested aggregations in a query, so you need to do the aggregation of the order products in a subquery.
And instead of CONCAT() and GROUP_CONCAT(), you can use JSON_ARRAYAGG() if you're running at least 5.7.22.
SELECT c.name, c.email, c.contact, c.registerDate, c.status,
JSON_ARRAYAGG(JSON_OBJECT("orderId", o.orderId, "total", o.total, "payment", o.payment, "products", op.products)) AS orders
FROM t_client AS c
INNER JOIN t_order AS o ON o.email = c.email
INNER JOIN (
SELECT op.orderId, JSON_ARRAYAGG(JSON_OBJECT("productId", p.productId, "product", p.product, "quantity", op.quantity)) AS products
FROM t_orderproduct AS op
INNER JOIN t_product AS p ON p.productId = op.productId
GROUP BY op.orderId
) AS op ON op.orderId = o.orderId
WHERE c.clientId = 1
GROUP BY c.clientId