Question

我有一张表格列出了人们的名字，他们的年龄，以及他们最喜欢的颜色。

我需要在SQL（In access）中创建一个查询，计算有多少人喜欢Red，以及有多少人喜欢Yellow。

到目前为止，我已经写过：

SELECT COUNT (*) as "People who like Yellow or Red"  
FROM Table1  
WHERE Table1.[Favorite Color]='Red'  
OR Table1.[Favorite Color]='Yellow';

但是这会返回喜欢黄色/红色（在我的情况下，5）

的人的总计数

我有三个喜欢黄色的人，还有两个喜欢红色的人，我怎样才能相互独立地展示这些数量呢？

Answer 1

通用解决方案使用GROUP BY运算符。这将根据谁喜欢什么颜色对数据进行分区，然后分别对每个组进行计数。

SELECT
  Table1.[Favorite Color],
  COUNT(*) as "People who like this color"
FROM Table1
GROUP BY Table1.[Favorite Color];

如果您只想在输出中使用红色和黄色，则可以添加该谓词：

SELECT
  Table1.[Favorite Color],
  COUNT(*) as "People who like this color"
FROM Table1
WHERE Table1.[Favorite Color] IN ('Red','Yellow')
GROUP BY Table1.[Favorite Color];

Answer 2

您可以使用CASE语句执行此操作：

SELECT SUM(CASE WHEN [Favorite Color]='Red' THEN 1 ELSE 0 END) as 'People who like Red'
       ,SUM(CASE WHEN [Favorite Color]='Yellow' THEN 1 ELSE 0 END) as 'People who like Yellow'
FROM Table1

Answer 3

select sum(case when [Favorite Color] = 'Red' then 1 else 0 end) as "People Who Like Red",
       sum(case when [Favorite Color] = 'Yellow' then 1 else 0 end) as "People Who Like Yellow"
from Table1

Answer 4

你可以尝试一下吗？

SELECT Count(*) AS ["People who like Yellow or Red"], Table1.[Favorite Color]
FROM Table1
GROUP BY Table1.[Favorite Color]
HAVING (((Table1.[Favorite Color])=[Enter Color]));

它会提示用户输入您指定红色或黄色的颜色，它会显示查询以计算您单独选择的颜色吗？

Answer 5

这是你在找什么？

select count(*) as "People who like Yellow or Red", Color
form Table1
group by color

计算SQL中的多个字段

5 个答案: