修改表和表添加字段

Mysql增加主键或者更改表的列为主键的sql语句

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 原字段名称 字段名称 字段类型 [是否允许非空];

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

alter table 表名称 modify 原字段名称 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;