mysql 修改已存在的表增加ID属性为auto_increment自动增长
今天有需要将已经存在表设置自动增长属性
具体如下
alter table customers change id id int not null auto_increment primary key;
扩展知识:
//添加字段并设置主键 ALTER TABLE tabelname ADD new_field_id int(5) unsigned default 0 not null auto_increment ,ADD primary key (new_field_id);
//加主关键字的索引 ALTER TABLE tablename ADD primary key(id);
//加索引 ALTER TABLE tablename CHANGE depno depno int(5) not null; ALTER TABLE tablename ADD INDEX 索引名 (字段名1[,字段名2 …]); ALTER TABLE tablename ADD INDEX emp_name (name);
//加唯一限制条件的索引 ALTER TABLE tablename ADD UNIQUE emp_name2(cardnumber);
//删除某个索引 ALTER TABLE tablename DROP INDEX emp_name;
//增加字段: ALTER TABLE table_name ADD field_name field_type;
//删除字段 ALTER TABLE table_name DROP field_name;
//重命名列 ALTER TABLE table_name CHANGE field_name1 field_name2 integer;
//调整字段顺序 ALTER TABLE `users` CHANGE `user_password` `user_password` varchar( 20 ) NOT NULL AFTER user_name;
//改变列的类型 ALTER TABLE table_name CHANGE field_name field_name bigint not null; ALTER TABLE infos CHANGE list list tinyint not null default '0';
//修改原字段名称及类型: ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;
//重命名表 ALTER TABLE table_name rename new_table_name;
//级联更新 和 删除(红色部分,不区分大小写 ) DROP TABLE IF EXISTS `mail_model`;create TABLE mail_model(id varchar(50) primary key not null ,mail_filename varchar(200),content varchar(2000))ENGINE=InnoDB DEFAULT CHARSET=gbk;
DROP TABLE IF EXISTS `mail_model_extend`;create TABLE mail_model_extend(id int(6) auto_increment not null primary key,rid varchar(50) not null,content varchar(2000),INDEX (RID),FOREIGN KEY (RID) REFERENCES mail_model(ID) ON DELETE CASCADE ON UPDATE CASCADE)ENGINE=InnoDB DEFAULT CHARSET=gbk;