自动递增重置为0,但不能插入id = 0的值.值> 0时不会发生

Question

我偶然发现了一个非常奇怪的行为:

想象一下,我们有一个表客户:

MariaDB [connections]> describe customers;
+--------------+-------------+------+-----+---------+----------------+
| Field        | Type        | Null | Key | Default | Extra          |
+--------------+-------------+------+-----+---------+----------------+
| customerId   | int(11)     | NO   | PRI | NULL    | auto_increment |
| customerName | varchar(50) | NO   |     | NULL    |                |
+--------------+-------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)

插入几个值:

insert into customers(customerName) values('Foo');
insert into customers(customerName) values('Bar');

然后删除所有内容并重置自动增量:

DELETE FROM customers;
ALTER TABLE customers AUTO_INCREMENT = 0;

现在,使用customerId = 0插入一个新值:

INSERT INTO customers(customerId,customerName) VALUES(0,'Site owner');

并看到结果:

MariaDB [connections]> select * from customers;
+------------+--------------+
| customerId | customerName |
+------------+--------------+
|          1 | Site owner   |
+------------+--------------+
1 row in set (0.00 sec)

customerId设置为1 !!!!

重复相同的步骤,但重置为5并插入5,一切正常:

MariaDB [connections]> delete from customers;
Query OK, 1 row affected (0.00 sec)

MariaDB [connections]> ALTER TABLE customers AUTO_INCREMENT = 5;
Query OK, 0 rows affected (0.00 sec)               
Records: 0  Duplicates: 0  Warnings: 0

MariaDB [connections]> INSERT INTO customers(customerId,customerName) VALUES(5,'Site owner');
Query OK, 1 row affected (0.00 sec)

MariaDB [connections]> select * from customers;
+------------+--------------+
| customerId | customerName |
+------------+--------------+
|          5 | Site owner   |
+------------+--------------+
1 row in set (0.00 sec)

这里发生了什么？如何使用插入值插入值"0"？(是的,我之后可以编辑,但由于各种原因,我的情况不实用).

谢谢!

Answer 1

我已经从链接中提到了答案

您可以使用:

SET [GLOBAL|SESSION] sql_mode='NO_AUTO_VALUE_ON_ZERO'

如此处所述,将阻止MySQL将INSERT/UPDATE ID 0解释为下一个序列ID.此类行为将限制为NULL.

这是我认为应用程序的非常糟糕的行为.您必须非常小心,它始终如一地使用,特别是如果您选择在以后实施复制.