Mysql 增加主键或者修改主键的sql语句操作

添加表字段

alter table table1 add transactor varchar(10) not null;
alter table table1 add id int unsigned not null auto_increment primary key

修改某个表的字段类型及指定为空或非空

alter table 表名称 change 字段名称 字段名称 字段类型 [是否允许非空];

alter table 表名称 modify 字段名称 字段类型 [是否允许非空];

alter table 表名称 modify 字段名称 字段类型 [是否允许非空];

修改某个表的字段名称及指定为空或非空

alter table 表名称 change 字段原名称 字段新名称 字段类型 [是否允许非空

删除某一字段

alter table mytable drop 字段 名;

添加唯一键

alter table `test2` add unique ( `userid`)

修改主键

alter table `test2` drop primary key ,add primary key ( `id` )

增加索引

alter table `test2` add index ( `id` )
alter table `category ` modify column `id` int(11) not null auto_increment first ,add primary key (`id`);

修改主键的sql语句块如下

mailbox 表新增字段

drop procedure if exists mailbox_column_update;
create procedure mailbox_column_update() begin
 -- 新增删除标志列
 if not exists(select 1 from information_schema.columns where table_schema='cbs' and table_name='mailbox' and column_name='delete_flag') then
   alter table mailbox add delete_flag int default 2 not null;
 end if;
 -- 新增删除日期列
 if not exists(select 1 from information_schema.columns where table_schema='cbs' and table_name='mailbox' and column_name='delete_date') then
   alter table mailbox add delete_date int default 0 not null;
 end if;
 -- 如果存在字段account_mail，则修改字段长度
 if exists(select 1 from information_schema.columns where table_schema='cbs' and table_name='mailbox' and column_name='email_account')
 then
  alter table mailbox modify column email_account varchar(320);
 end if;
 -- 如果不存在主键列，则设置双主键
 if ((select count(*) from information_schema.key_column_usage where table_schema ='cbs' and table_name='mailbox' and constraint_name ='primary' and (column_name ='email_account' or column_name = 'company_id'))=0)then
    alter table mailbox add primary key (company_id,email_account);
 -- 如果只存在一个主键列
 elseif ((select count(*) from information_schema.key_column_usage where table_schema ='cbs' and table_name='mailbox' and constraint_name ='primary' and (column_name ='email_account' or column_name = 'company_id'))<2)then
    alter table mailbox drop primary key,add primary key (company_id,email_account);
 end if;
  
end;
call mailbox_column_update();
drop procedure if exists mailbox_column_update;

补充：mysql 修改主键自增,新增联合主键

alter table `onduty_history`
modify column `id` int(11) not null auto_increment first ,
modify column `name` varchar(50) character set utf8 collate utf8_general_ci not null after `id`,
modify column `onduty_date` datetime not null after `name`,
add unique key (`id`),
add primary key (`name`, `onduty_date`);

以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。