mysql - MySql <> NULL 和 IS NOT NULL 之间的区别

Question

在我的数据库中有一个 varchar(255) 列，对于某些记录，它包含空值，当我解雇这个

SELECT * FORM my_table where some_column <> NULL;

没有返回

但是什么时候被解雇

SELECT * FORM my_table where some_column IS NOT NULL;

我得到了想要的记录

您能解释一下它们之间的主要区别是什么以及何时使用 <> 和 != 运算符吗？

Answer 1

From the Mysql 8 Reference:

You cannot use arithmetic comparison operators such as =, <, or <> to test for NULL. Because the result of any arithmetic comparison with NULL is also NULL, you cannot obtain any meaningful results from such comparisons.