SQL Server选择带计数查询

Question

我在SQL Server中有以下表格。我想要做的是将家庭分组与成员总数。

得到这样的东西

任何帮助将不胜感激。

Answer 1

您可以尝试将case when表达式与Aggregate函数

一起使用

SELECT COUNT(CASE WHEN name like '%tayson%' then 1 end) as tayson,
      COUNT(CASE WHEN name like '%ross%' then 1 end) as ross,
      COUNT(CASE WHEN name like '%dee%' then 1 end) as dee
FROM T

sqlfiddle：http://sqlfiddle.com/#!18/ef5de/2

<强>结果：

| tayson | ross | dee |
|--------|------|-----|
|      3 |    3 |   1 |

Answer 2

试试这个：

使用group by

分隔姓氏和计数

select substring(name, CHARINDEX(' ', name)+1, len(name)-(CHARINDEX(' ', name)-1)) as lastname,count(*) as total
from your_table
group by substring(name, CHARINDEX(' ', name)+1, len(name)-(CHARINDEX(' ', name)-1));

如有任何疑问，请与我联系。

Answer 3

首先，你需要将名称分成两列，（名字和姓氏），如果名称用空格分隔（例如Mike Tyson），那么你可以这样做：

SELECT 
       SUBSTRING(name, 1, CHARINDEX(' ', name) - 1) AS FirstName,     
       SUBSTRING(name, CHARINDEX(' ', name) + 1, LEN(name) - CHARINDEX(' ', name)) AS LastName 
FROM yourTable

这会给你：

| Firstname | Lastname |
|-----------|----------|
|      Mike |   tayson |
|      John |     ross |
|    Oliver |   tayson |
|     Aaron |      dee |
|    Robort |     ross |
|      Jack |     ross |
|     Honry |   tayson |

现在，使用它来根据姓氏计算总成员数。

SELECT 
    LastName,
    COUNT(FirstName) AS TotalMembers 
FROM (
SELECT 
       SUBSTRING(name, 1, CHARINDEX(' ', name) - 1) AS FirstName,     
       SUBSTRING(name, CHARINDEX(' ', name) + 1, LEN(name) - CHARINDEX(' ', name)) AS LastName  
FROM yourTable
) D 
GROUP BY LastName

这会给你：

| LastName | TotalMembers |
|----------|--------------|
|      dee |            1 |
|     ross |            3 |
|   tayson |            3 |

现在，您需要使用PIVOT将行旋转为列：

SELECT * 
FROM (
SELECT 
       SUBSTRING(name, 1, CHARINDEX(' ', name) - 1) AS Firstname,     
       SUBSTRING(name, CHARINDEX(' ', name) + 1, LEN(name) - CHARINDEX(' ', name)) AS Lastname 
FROM yourTable
) D 
PIVOT
(
COUNT(FirstName)
FOR  Lastname IN (tayson, ross, dee)
) AS pvt 

这会给你：

| tayson | ross | dee |
|--------|------|-----|
|      3 |    3 |   1 |