MySQL - 查询所有用户没有约会 [英] MySQL - Query All users WITHOUT an appointment

问题描述

如果我有两个表：用户和约会。我如何查询数据库以找到如下所示的内容：

If I have two tables: Users and Appointments. How would I query the db to find something like the following:

SELECT * FROM users WHERE (none of: appointments.user = user.id)

我假设我需要一些类型的约会表，确定从哪里开始。

I am assuming I would need some type of join with the appointments table, just not sure where to start.

推荐答案

SELECT * FROM users 
LEFT JOIN Appointments ON Users.UserID=Appointments.UserID
WHERE Appointments.UserID is null

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