MySQL的計數獨特的客戶所購買的某些項目

Question

tbl_products

+-------+---------+---------+ 
| id | item | Customer| 
+-------+---------+---------+ 
| 1 | Apple | brad | 
| 2 | Apple | alex | 
| 3 | Apple | brad | 
| 4 | Apple | brad | 
| 5 | Apple | tim  | 
| 6 | Orange | brad | 
| 7 | Orange | steve | 
| 8 | Orange | alex | 
+-------+---------+---------+ 

客戶有多少獨特的購買蘋果？ 答案應該是： 蘋果3

Answer 1

試試這個：

SELECT COUNT(DISTINCT Customer) 
FROM tbl_products 
WHERE item ='Apple'