当我们在AUTO_INCREMENT列中插入NULL值时,MySQL将返回序列号。
mysql> Create table employee(id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, Name Varchar(10)); mysql> Insert into employee(id, Name) values(NULL, 'Gaurav'); mysql> Select * from employee; +----+---------+ | id | Name | +----+---------+ | 1 | Gaurav | +----+---------+ 1 row in set (0.00 sec)