串的出现次数

Question

我有车

id | brand | model 
1 | bmw | 525 
1 | bmw | 533 
2 | audi | a8 
... 

我想利用特定ID的品牌出现，在这个例子中的列表：

id | brand | model | n 
1 | bmw | 525 | 2 
1 | bmw | 533 | 2 
2 | audi | a8 | 1 
... 

请，我需要这方面的帮助。

Answer 1

使用count()作为窗口函数：

select c.*, count(*) over (partition by brand) as n 
from cars c; 

Answer 2

使用相关子查询数：

select c1.id, c1.brand, c1.model, (select count(*) from cars c2 
            where c2.id = c1.id) 
from cars c1 

Answer 3

你可以这样做：

SELECT T1.id,T1.brand,T1.model,T2.n 
FROM TableName T1 JOIN 
(SELECT id,brand,COUNT(1) as n 
FROM TableName 
GROUP BY id,brand) as T2 ON T1.id=T2.id AND T1.brand=T2.brand 

结果：

id brand model n 
1 bmw  525  2 
1 bmw  533  2 
2 audi a8  1 

样品结果于SQL Fiddle。