從表中選擇當列的值沒有在另一個表中存在

Question

SELECT Id, Name, Lastname 
FROM customers AS c, Places AS p, 
WHERE c.customer_ID = p.customer_ID 

我的問題是，我想阻止顯示一排中存在的另一個表查詢（階段）

Answer 1

你可以做一個LEFT JOIN和檢查空。

SELECT Id, Name, Lastname 
FROM customers AS c LEFT JOIN Places AS p ON c.customer_ID = p.customer_ID 
WHERE p.customer_ID IS NULL 

Answer 2

結果您可以使用：

SELECT Id, Name, Lastname 
FROM customers AS c JOIN Places AS p USING(customer_ID) 

這是用in/exists可以更快的方式。

Answer 3

添加

and not exists 
(subquery to select your exclusions) 

到您的查詢

Answer 4

我想你想是這樣的：

SELECT Id, Name, Lastname FROM customers, WHERE customer_ID NOT IN (SELECT customer_ID FROM Places)