mysql - 数一数市场有多少产品

Question

目标

数一数市场有多少产品。

问题

查询只返回第一个结果，我想要inMarketsQuantity每个产品的结果。

场景

这是查询：

Select product.Name As productName, 
       Count(marketProducts.ProductId) As inMarketsQuantity
From products As product
Join market_products As marketProducts On product.Id = marketProducts.ProductId
Join markets As market On marketProducts.MarketId = market.Id

这是结果：

+---------------+-------------------+
| productName   | inMarketsQuantity |
+---------------+-------------------+
| Playstation 3 | 15                |
+---------------+-------------------+

这就是我所期待的：

+---------------+-------------------+
| productName   | inMarketsQuantity |
+---------------+-------------------+
| Playstation 3 | 10                |
+---------------+-------------------+
| Xbox          | 5                 |
+---------------+-------------------+

我已经尝试过的

我已经尝试过以下查询，但我收到了SQL 错误 (1064)：

Select product.Name As productName, 
       Distinct(Count(marketProducts.ProductId)) As inMarketsQuantity

[...]

Answer 1

尝试分组ProductId：

Select product.Name As productName,
    Count(marketProducts.ProductId) As inMarketsQuantity
From products As product
    Join market_products As marketProducts On product.Id = marketProducts.ProductId
    Join markets As market On marketProducts.MarketId = market.Id
GROUP BY marketProducts.ProductId

Answer 2

Select product.Name As productName, 
       Count(marketProducts.ProductId) As inMarketsQuantity
From products As product
Join market_products As marketProducts On product.Id = marketProducts.ProductId
Join markets As market On marketProducts.MarketId = market.Id GROUP BY product.Name