For vehicles with 2 or more suppliers, COUNT the number of parts (vehicle_part) and suppliers (supplier) per vehicle答案

【问题标题】：For vehicles with 2 or more suppliers, COUNT the number of parts (vehicle_part) and suppliers (supplier) per vehicleFor vehicles with 2 or more suppliers, COUNT the number of parts (vehicle_part) and suppliers (supplier) per vehicle
【发布时间】：2022-12-27 20:32:25
【问题描述】：

Data model

- Goal:Count the number of suppliers (supplier) and parts (vehicle_part) for each vehicle for which there are two or more suppliers.

- requirements:Expected columns: vehicle_name, vehicle_part_count, supplier_count in that order

【问题讨论】：

标签： sql join group-by count

【解决方案1】：

Goal: Count the number of suppliers (supplier) and parts (vehicle_part) for each vehicle for which there aretwo or more suppliers<-- for each part ?

There could be like 5 parts of a vehicle so 1 supplier per part = 5 different suppliers, does that count or not ?

【讨论】：

How I could Count the parts and suppliers for each car. as you commented 5 parts could have 5 different suppliers
Could 2 different vehicle_part_ids have same supplier ?
Indeed, there may be a part supplied by more then One Supplier
That supplier should also appear once in the count right ?
let's assume that exact behavor I'm looking for

【解决方案2】：

select v.vehicle_name, count(distinct vp.vehicle_part_id) as vehicle_part_count, count(distinct vps.supplier_id) as supplier_count from "codinGame".vehicle_part vp join "codinGame".vehicle_part_supplier vps on vp.vehicle_part_id=vps.vehicle_part_id join "codinGame".vehicle v on vp.vehicle_id = v.vehicle_id group by v.vehicle_name having count(distinct vps.supplier_id)>=2;

【讨论】：