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共生网络。如有错误或未考虑完全的地方，望不吝赐教。