sql - SQL Server 2008：计算存储在类别中的记录数

Question

我是 SQL Server 的新手，遇到了一个令我困惑的问题。

我有 2 个数据表Category和Product. 下面是详细的表格。

类别：

------------------------------------------------------
 categoryId | categoryName      | desc
------------------------------------------------------
 1          | Shirt             | Men's Shirt
 2          | Jeans             | Men's Pants
 3          | Accessories       | Women's Accessories
------------------------------------------------------

产品

---------------------------------------------------------------
productID   | desc                     | categoryId
---------------------------------------------------------------
 1          | Slim-fit Classic Shirt   | 1
 2          | Denim Slim-fit jeans     | 2
 3          | Denim Regular-fit jeans  | 2
 4          | Bracelet                 | 3
---------------------------------------------------------------

我怎样才能得到如下的确切输出？

-------------------------------------------------------------------
 categoryId | categoryName      | numOfRecord | desc
-------------------------------------------------------------------
 1          | Shirt             | 1           | Men's Shirt
 2          | Jeans             | 2           | Men's Pants
 3          | Accessories       | 1           | Women's Accessories
-------------------------------------------------------------------

对不起我的英语不好。

Answer 1

您可以使用COUNT和GROUP BY。

尝试这个：

SELECT c.categoryId, c.categoryName, count(*) as numOfRecord, p.[desc]
FROM dbo.Category AS c INNER JOIN dbo.Product AS p
ON c.categoryId = p.categoryId
GROUP BY c.categoryId, c.categoryName, p.[desc];