Mysql 增加主键或者修改主键的sql语句操作

添加表字段

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1 2	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

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1	ALTER TABLE mytable DROP 字段 名;

添加唯一键

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

修改主键

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

增加索引

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1 2	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`);

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服务器之家。如有错误或未考虑完全的地方，望不吝赐教。

原文链接：https://blog.csdn.net/qq_35211818/article/details/79709657