SQL不同的組通過

Question

SQL：集團按國家&計數，很簡單，但我對我的表1失去 我

Country | Optin | 
-------------------------- 
USA  | 1  | 
USA  | 1  |  
GERMANY | 0  |  
USA  | 1  |   
GERMANY | 1  |   
JAPON  | 1  | 

我想回到這個表，我只是想通過國家時選擇啓用計數部分= 1

Country | Optin | 
-------------------------- 
USA  | 3  | 
GERMANY | 1  | 
JAPON  | 1  | 


SELECT * 
FROM Table1 
WHERE Optin = 1 
GROUP BY Country 

Answer 1

我只想按國家統計OPTIN部分= 1

時210

使用COUNT與GROUP BY country（或SUM因爲所有optin的返回= 1）：

SELECT Country, COUNT(optin) 
FROM table1 
WHERE optin = 1 
GROUP BY country; 

SQL Fiddle Demo

Answer 2

SELECT Country, SUM(CASE WHEN Optin = 1 THEN 1 ELSE 0 END) totalOptin 
FROM TableName 
GROUP BY Country 

• SQLFiddle Demo