SQL 服务器 Select 计数 > 1

Question

项目：经典 ASP VBScript / SQL Server 2012

我有 2 个 table，Products 和 Categories。

我想构建一个 SQL 查询，它将 return 仅具有多个的类别] 产品。

2个table之间的公共键是列Category_id（存在于Products table和Categories table).

Answer 1

你试试这个：

SELECT * 
FROM Categories C
WHERE C.Category_id IN ( SELECT P.Category_id FROM Products P GROUP BY P.Category_id HAVING COUNT(*) > 1)

Answer 2

您可以对此类查询使用 having 子句，该子句在完成所有聚合后过滤您的数据集：：

declare @Categories table(CategoryID int); declare @Products table(ProdID int, CategoryID int); insert into @Categories values(1),(2),(3); insert into @Products values(10,1),(20,1),(30,2),(40,2),(50,3); select c.CategoryID ,count(1) as ProductCount from @Categories c left join @Products p on(c.CategoryID = p.CategoryID) group by c.CategoryID having count(1) > 1;

输出：

+------------+--------------+ | CategoryID | ProductCount | +------------+--------------+ | 1 | 2 | | 2 | 2 | +------------+--------------+

Answer 3

将简单 Group by 与 Having 用作下一个演示：-

create table Products (ProductID int, name varchar(50), Category_id int )
insert into Products 
values
(1,'aaaa',1),
(2,'bbbb',1),
(3,'ccccc',2),
(4,'11111',2),
(5,'11111ccc',3)

create table Categories (Category_id int, name varchar(50))
insert into Categories 
values
(1,'Letters'),
(2,'Numbers'),
(3,'NumbersAndLetters')

-- CategoryID = 3 has only one product ..

select p.Category_id ,count(p.ProductID) CountProducts from 
Products p inner join Categories c
on p.Category_id = c.Category_id
group by p.Category_id
having count(p.ProductID) > 1

结果：-

Category_id CountProducts
   1              2
   2              2

SQL 服务器 Select 计数 > 1

SQL Server Select count > than 1

sql-server

select

asp-classic