Mysql 4 vs Mysql 5 插入时自动递增字段
我一路上学到了这一点，但不知道在哪里读到或听到它，因为我在网上找不到任何支持它的东西，但我记得当从 mysql4.x 升级到 mysql5.x 时，其中之一所需的更改是插入的自动增量字段必须从 '' 更改为 NULL（如果包含）。
我知道无论如何都不需要在插入中包含它，但只是为了兴趣点......
Mysql 4.x 将允许： INSERT INTO TABLE (table_id, name, location) VALUES ('', 'john', 'NY');
但 mysql 5.x 必须有： INSERT INTO TABLE (table_id, name, location) VALUES (NULL, 'john', 'NY');
我在 mysql 的网站上找不到任何信息来支持这一点，但我知道它在 mysql 5.x 中抛出一个错误，并且知道它在 4.x 中与 '' 一起工作，但这在哪里记录？
I've learned this along the way but can't figure out where I read it or heard it, as there is nothing I have found online supporting it, but I remember that when upgrading from mysql4.x to mysql5.x, one of the required changes was that the auto-increment field for inserts had to change from '' to NULL if it was included.
I know its not required to have in the insert anyway, but just for point of interest...
Mysql 4.x would allow:
INSERT INTO TABLE (table_id, name, location) VALUES ('', 'john', 'NY');
But mysql 5.x had to have:
INSERT INTO TABLE (table_id, name, location) VALUES (NULL, 'john', 'NY');
I can't find any information on mysql's site to support this, but I know for a fact it throws an error in mysql 5.x and know it worked with '' in 4.x, but where is this documented?
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4.1 和 5.0 文档指出需要 0 或 NULL：
Both the 4.1 and 5.0 docs state that 0 or NULL is required:
没关系，mysql内部仍然转换为整数
mysql> CREATE TABLE some_test ( id int(10) unsigned NOT NULL auto_increment, primary key(id)); Query OK, 0 rows affected (0.00 sec) mysql> insert into some_test values (''); Query OK, 1 row affected, 1 warning (0.00 sec) mysql> show warnings; +---------+------+------------------------------------------------------+ | Level | Code | Message | +---------+------+------------------------------------------------------+ | Warning | 1264 | Out of range value adjusted for column 'id' at row 1 | +---------+------+------------------------------------------------------+ 1 row in set (0.00 sec) mysql> select * from some_test; +----+ | id | +----+ | 1 | +----+ 1 row in set (0.00 sec)但是，我建议使用0来避免这个警告
It does not matter, mysql internally still convert to integer
mysql> CREATE TABLE some_test ( id int(10) unsigned NOT NULL auto_increment, primary key(id)); Query OK, 0 rows affected (0.00 sec) mysql> insert into some_test values (''); Query OK, 1 row affected, 1 warning (0.00 sec) mysql> show warnings; +---------+------+------------------------------------------------------+ | Level | Code | Message | +---------+------+------------------------------------------------------+ | Warning | 1264 | Out of range value adjusted for column 'id' at row 1 | +---------+------+------------------------------------------------------+ 1 row in set (0.00 sec) mysql> select * from some_test; +----+ | id | +----+ | 1 | +----+ 1 row in set (0.00 sec)However, I will suggest use 0 to avoid this warning