将auto_increment添加到主键

I have a strange problem with mysql.

我对mysql有一个奇怪的问题。

I am trying to alter a table's column which is a primary key and has an auto_increment constraint defined on it. This is also a foreign key reference for multiple other tables. I need to change the length of this column in both , parent and all children.

我正在尝试修改表的列，它是一个主键，并且在表上定义了一个auto_increment约束。这也是多个其他表的外键引用。我需要修改这个列的长度，包括父元素和所有子元素。

set foreign_key_checks=0;
alter table Parent  modify Identifier smallint(10) unsigned;
alter table Child_1 modify FK_Identifier smallint(10) unsigned;
alter table Child_2 modify FK_Identifier smallint(10) unsigned;
alter table Child_3 modify FK_Identifier  smallint(10) unsigned;
alter table Child_4 modify FK_Identifier smallint(10) unsigned;
alter table Child_5 modify FK_Identifier smallint(10) unsigned;
set foreign_key_checks=1;

This removes the auto increment on the parent table. What would be the best way to add the constraint back ?

这将删除父表上的自动增量。将约束添加回的最佳方法是什么?

The below seems to be failing.

下面的似乎是失败的。

mysql> ALTER TABLE Parent MODIFY Identifier smallint(10) PRIMARY KEY AUTO_INCREMENT;
ERROR 1068 (42000): Multiple primary key defined


ALTER TABLE Parent MODIFY Identifier smallint(10) AUTO_INCREMENT;
------------------------
LATEST FOREIGN KEY ERROR
------------------------
110125 15:49:08 Error in foreign key constraint of table db/Child_1:
there is no index in referenced table which would contain
the columns as the first columns, or the data types in the
referenced table do not match to the ones in table. Constraint:
,
  CONSTRAINT Child_1_ibfk_1 FOREIGN KEY (FK_Identifier) REFERENCES RoomProfile (Identifier) ON DELETE CASCADE ON UPDATE CASCADE
The index in the foreign key in table is PRIMARY

Is there a better way to achieve this ?

有更好的方法实现这一点吗?

Edit : Show create is (after alter) :

编辑:Show create is (after alter):

  CREATE TABLE `Parent` (
  `Identifier` smallint(10) unsigned NOT NULL default '0',
  `Name` varchar(20) default NULL,
  `Description` varchar(100) default NULL,
   PRIMARY KEY  (`Identifier`),
   UNIQUE KEY `Name` (`Name`),
  ) ENGINE=InnoDB DEFAULT CHARSET=latin1 | 

before alter

在改变之前

`Identifier` smallint(5) unsigned NOT NULL AUTO_INCREMENT,

Thanks!

谢谢!

1 个解决方案

#1

You don't need to specify PRIMARY KEY in the MODIFY statement:

您不需要在MODIFY语句中指定主键:

ALTER TABLE Parent MODIFY Identifier smallint(10) AUTO_INCREMENT;