postgresql - 不能嵌套聚合函数调用。如何以漂亮的 json 格式格式化此查询？

Question

我正在尝试创建一个以漂亮的 json 格式返回数据的 psql 查询。最初对于我们使用 sequelize 的项目，我正在尝试将其转换为纯 psql。我要找的格式如下-

...
vehicles:
[
  {
    services: 
    [
      {
        name: "example"
        duration: "example"
      }
    ]
    id: 1
    registration: "example"
  }
]
...

以下是我首先尝试但得到错误的方法。 错误：聚合函数调用不能嵌套

SELECT
   "Bookings"."id",
   "Bookings"."startTime",
   "Bookings"."code",
   "Bookings"."statusId",
   "Bookings"."address",
   "Bookings"."latitude",
   "Bookings"."longitude",
   "Bookings"."createdAt",
   "Bookings"."overridePrice",
   
   json_build_object(
       'fullName', "customer"."fullName",
       'id', "customer"."id"
   ) AS "customer",
   
   json_agg(json_build_object(
       'fullName', "serviceProvider"."fullName", 
       'id', "serviceProvider"."id"
   )) AS "serviceProvider",
   
-- Array of vehicles, this is where the issue lies
   json_agg(
       json_build_object(
       'services', json_agg(
           json_build_object(
                'name', "ServiceHistories"."name",
                'duration', "ServiceHistories"."duration"
            )
       ),
       'id', "Vehicles"."id", 
       'registration', "Vehicles"."registration"
   )) AS "vehicles",
--  Everything else works fine
   
   json_agg(
       json_build_object(
           'amount', "payments"."amount",
           'amountFromGiftCard', "payments"."amountFromGiftCard"
       )
   ) AS "payments"
   
FROM
   "Bookings",
   "Users" AS "customer",
   "Users" AS "serviceProvider",
   "BookingServiceProviders",
   "BookingVehicleServices",
   "BookingVehicles",
   "Vehicles",
   "Payments" AS "payments",
   "ServiceHistories"
WHERE
    "Bookings"."isDeleted" IS NOT true AND
    "Bookings"."statusId" != 4 AND
    "Bookings"."customerId" = "customer"."id" AND "customer"."userTypeId" = 1 AND
    "Bookings"."id" = "BookingServiceProviders"."BookingId" AND
    "BookingServiceProviders"."UserId" = "serviceProvider"."id" AND
    "Bookings"."id" = "BookingVehicles"."BookingId" AND
    "Vehicles"."id" = "BookingVehicles"."VehicleId" AND
    "Bookings"."id" = "payments"."bookingId" AND
    "BookingVehicles"."id" = "BookingVehicleServices"."BookingVehicleId" AND
    "ServiceHistories"."bookingId" = "Bookings"."id"
GROUP BY 
    "Bookings"."id",
    "customer"."id",
    "customer"."fullName"
Order by "startTime" ASC

做了一些谷歌搜索后，我发现我可能需要对服务数组进行子查询。以下是我尝试过的，但查询会无限期运行。

SELECT
   "Bookings"."id",
   "Bookings"."startTime",
   "Bookings"."code",
   "Bookings"."statusId",
   "Bookings"."address",
   "Bookings"."latitude",
   "Bookings"."longitude",
   "Bookings"."createdAt",
   "Bookings"."overridePrice",
   
   json_build_object(
       'fullName', "customer"."fullName",
       'id', "customer"."id"
   ) AS "customer",
   
   json_agg(json_build_object(
       'fullName', "serviceProvider"."fullName", 
       'id', "serviceProvider"."id"
   )) AS "serviceProvider",
   
   -- Issue lies here
   json_agg(
       json_build_object(
           'services', (
               SELECT 
                    json_agg(json_build_object(
                        'name', "ServiceHistories"."name",
                       'duration', "ServiceHistories"."duration"
                    ))
               FROM
                    "ServiceHistories"
               WHERE
                    "ServiceHistories"."bookingId" = "Bookings"."id"
           ),
       'id', "Vehicles"."id", 
       'registration', "Vehicles"."registration"
   )) AS "vehicles",
   -- End of issue
   
   json_agg(
       json_build_object(
           'amount', "payments"."amount",
           'amountFromGiftCard', "payments"."amountFromGiftCard"
       )
   ) AS "payments"
   
FROM
   "Bookings",
   "Users" AS "customer",
   "Users" AS "serviceProvider",
   "BookingServiceProviders",
   "BookingVehicleServices",
   "BookingVehicles",
   "Vehicles",
   "Payments" AS "payments"
WHERE
    "Bookings"."isDeleted" IS NOT true AND
    "Bookings"."statusId" != 4 AND
    "Bookings"."customerId" = "customer"."id" AND "customer"."userTypeId" = 1 AND
    "Bookings"."id" = "BookingServiceProviders"."BookingId" AND
    "BookingServiceProviders"."UserId" = "serviceProvider"."id" AND
    "Bookings"."id" = "BookingVehicles"."BookingId" AND
    "Vehicles"."id" = "BookingVehicles"."VehicleId" AND
    "Bookings"."id" = "payments"."bookingId" AND
    "BookingVehicles"."id" = "BookingVehicleServices"."BookingVehicleId"
GROUP BY 
    "Bookings"."id",
    "customer"."id",
    "customer"."fullName"
Order by "startTime" ASC

如果有人可以帮助或指出正确的方向，我将不胜感激。

** 编辑 **

我通过添加更多关于表如何关联的 where 子句来使其工作，现在服务在车辆数组中正确返回。可悲的是它的超级慢。我让它工作得更快，但是当它应该只是与特定预订相关的服务时，却出现了重复的服务。

SELECT
   bookings."id",
   bookings."startTime",
   bookings."code",
   bookings."statusId",
   bookings."address",
   bookings."latitude",
   bookings."longitude",
   bookings."createdAt",
   bookings."overridePrice",
   
   json_build_object(
       'fullName', "customer"."fullName",
       'id', "customer"."id"
   ) AS "customer",
   
   json_agg(json_build_object(
       'fullName', "serviceProvider"."fullName", 
       'id', "serviceProvider"."id"
   )) AS "serviceProvider",
   
   json_agg(
       json_build_object(
           'amount', "payments"."amount",
           'amountFromGiftCard', "payments"."amountFromGiftCard"
       )
   ) AS "payments",
   
    (
        SELECT 
        (nested_vehicles)
        FROM (
            SELECT
                "Vehicles".id as vehicle_id,
                "Vehicles".registration,
                (
                    SELECT 
                        json_agg(nested_services)
                    FROM (
                        SELECT
                            "ServiceHistories"."id",
                            "ServiceHistories"."name",
                            "ServiceHistories"."duration"
                        FROM 
                            "ServiceHistories", "BookingVehicleServices", "BookingVehicles"
                        WHERE 
                            "ServiceHistories"."vehicleId" = "Vehicles"."id" AND 
                            "ServiceHistories"."id" = "BookingVehicleServices"."ServiceHistoryId" AND
                            bookings.id = "BookingVehicles"."BookingId" AND
                            "Vehicles"."id" = "BookingVehicles"."VehicleId" AND
                            "ServiceHistories"."bookingId" = bookings.id 
                            
                    ) AS nested_services
                ) AS services
            FROM 
                "Vehicles", "BookingVehicles"
            WHERE "Vehicles"."id" = "BookingVehicles"."VehicleId" AND bookings.id = "BookingVehicles"."BookingId"
            GROUP BY "Vehicles"."id"
        ) AS nested_vehicles
    ) AS vehicles
FROM 
    "Bookings" as bookings,
    "Users" AS "customer",
    "Users" AS "serviceProvider",
    "BookingServiceProviders",
    "Payments" AS "payments"
WHERE
    bookings."isDeleted" IS NOT true AND
    bookings."statusId" != 4 AND
    bookings."customerId" = "customer"."id" AND "customer"."userTypeId" = 1 AND
    bookings."id" = "BookingServiceProviders"."BookingId" AND
    "BookingServiceProviders"."UserId" = "serviceProvider"."id" AND
    bookings."id" = "payments"."bookingId"
GROUP BY 
    bookings."id",
    "customer"."id",
    "customer"."fullName"
Order by "startTime" ASC

不太确定在这里做什么。我可能只是单独返回服务，然后在外部格式化它们：/

Answer 1

错误：聚合函数调用不能嵌套

不确定最佳实践，但我使用 subqueries 或 Common Table Expressions (CTE)。

第一个聚合函数调用来自子查询/CTE，第二个聚合函数调用来自查询。

-- Common Table Expressions
WITH regional_sales AS (
        SELECT region, SUM(amount) AS total_sales
        FROM orders
        GROUP BY region
     ), top_regions AS (
        SELECT region
        FROM regional_sales
        WHERE total_sales > (SELECT SUM(total_sales)/10 FROM regional_sales)
     )
SELECT region,
       product,
       SUM(quantity) AS product_units,
       SUM(amount) AS product_sales
FROM orders
WHERE region IN (SELECT region FROM top_regions)
GROUP BY region, product;