mysql - 从另一个表中不存在列值的表中选择

Question

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

我的问题是，我想阻止显示另一个表中存在的行的查询结果（阶段）

Answer 1

您可以执行 LEFT JOIN 并检查是否为空。

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

添加

and not exists
(subquery to select your exclusions)

对您的查询

Answer 3

你可以使用：

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

这是您可以使用的更快的方法in/exists。

Answer 4

我想你想要这样的东西：

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