添加表字段
|
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
|
1
|
ALTER TABLE mytable DROP 字段 名; |
添加唯一键
|
1
|
ALTER TABLE `test2` ADD UNIQUE ( `userid`) |
修改主键
|
1
|
ALTER TABLE `test2` DROP PRIMARY KEY ,ADD PRIMARY KEY ( `id` ) |
增加索引
|
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
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
|
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
|
1
2
3
4
5
6
|
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
