Mysql 增加主键或者修改主键的sql语句操作_Mysql

Mysql 增加主键或者修改主键的sql语句操作

2021-04-13 20:04橙子AQA Mysql

这篇文章主要介绍了Mysql 增加主键或者修改主键的sql语句操作，具有很好的参考价值，希望对大家有所帮助。一起跟随小编过来看看吧

添加表字段

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									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];

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

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									ALTER TABLE mytable DROP 字段 名;

添加唯一键

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									ALTER TABLE `test2` ADD UNIQUE ( `userid`)

修改主键

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									ALTER TABLE `test2` DROP PRIMARY KEY ,ADD PRIMARY KEY ( `id` )

增加索引

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									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

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									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

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									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`);