獲取與客戶不匹配標準

Question

給出一個簡單的表格（訂單明細/歷史類的話）行數和產品：

+--------------------+ 
| customer | product | 
+--------------------+ 
| Smith | p1  | 
| Smith | p3  | 
| Jones | p1  | 
| Jones | p2  | 
| Davis | p3  | 
| Davis | p9  | 
| Brown | p1  | 
| Brown | p2  | 
| Brown | p5  | 
+----------+---------+ 

我想列出從未訂購的產品所有客戶p1，即戴維斯在上述數據集。

這是我開始，但是，當然，它不工作，我不能想到哪兒去旁邊：

select 
    customer, 
    count(*) as c 
where product='p1' 
    and c = 0 

Answer 1

這裏有一種方法，使用聚合查詢：

select customer 
from t 
group by customer 
having sum(case when product = 'p1' then 1 else 0 end) = 0 

這給你表中的所有客戶。如果你有客戶的單獨列表，那麼你可以使用：

select customer 
from customerTable 
where customer not in (select customer from t where product = 'p1') 

Answer 2

嘗試了這一點：

select customer 
from MyTable 
where customer not in (select customer from MyTable where Product = 'P1') 

Answer 3

您也可以使用這種方法

SELECT t.CustomerName 
FROM Table t 
WHERE NOT EXISTS (SELECT 1 
        FROM Table t2 
        WHERE t2.CustomerName = t.CustomerName 
        AND t2.ProductName = 'p1')