MySQL添加字段: alter table `user_movement_log` Add column GatewayId int not null default 0 AFTER `Regionid` (在哪个字段后面添加) 删除字段: alter table `user_movement_log` drop column Gatewayid 调整字段顺序: ALTER TABLE `user_movement_lo
MySQL添加字段:
alter table `user_movement_log` Add column GatewayId int not null default 0 AFTER `Regionid` (在哪个字段后面添加)
删除字段:
alter table `user_movement_log` drop column Gatewayid
调整字段顺序:
ALTER TABLE `user_movement_log` CHANGE `GatewayId` `GatewayId` int not null default 0 AFTER RegionID //主键 alter table tabelname add new_field_id int(5) unsigned default 0 not null auto_increment ,add primary key (new_field_id);//增加一个新列 alter table t2 add d timestamp; alter table infos add ex tinyint not null default '0';//删除列 alter table t2 drop column c;//重命名列 alter table t1 change a b integer; //改变列的类型 alter table t1 change b b bigint not null; alter table infos change list list tinyint not null default '0'; //重命名表 alter table t1 rename t2;加索引 mysql> alter table tablename change depno depno int(5) not null; mysql> alter table tablename add index 索引名 (字段名1[,字段名2 …]); mysql> alter table tablename add index emp_name (name);加主关键字的索引 mysql> alter table tablename add primary key(id);加唯一限制条件的索引 mysql> alter table tablename add unique emp_name2(cardnumber);删除某个索引 mysql>alter table tablename drop index emp_name;修改表:
增加字段:
mysql> ALTER TABLE table_name ADD field_name field_type;修改原字段名称及类型: mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;删除字段: mysql> ALTER TABLE table_name DROP field_name;

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了关于架构原理的相关内容,MySQL Server架构自顶向下大致可以分网络连接层、服务层、存储引擎层和系统文件层,下面一起来看一下,希望对大家有帮助。

mysql的msi与zip版本的区别:1、zip包含的安装程序是一种主动安装,而msi包含的是被installer所用的安装文件以提交请求的方式安装;2、zip是一种数据压缩和文档存储的文件格式,msi是微软格式的安装包。

方法:1、利用right函数,语法为“update 表名 set 指定字段 = right(指定字段, length(指定字段)-1)...”;2、利用substring函数,语法为“select substring(指定字段,2)..”。

在mysql中,可以利用char()和REPLACE()函数来替换换行符;REPLACE()函数可以用新字符串替换列中的换行符,而换行符可使用“char(13)”来表示,语法为“replace(字段名,char(13),'新字符串') ”。

转换方法:1、利用cast函数,语法“select * from 表名 order by cast(字段名 as SIGNED)”;2、利用“select * from 表名 order by CONVERT(字段名,SIGNED)”语句。

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了关于MySQL复制技术的相关问题,包括了异步复制、半同步复制等等内容,下面一起来看一下,希望对大家有帮助。

在mysql中,可以利用REGEXP运算符判断数据是否是数字类型,语法为“String REGEXP '[^0-9.]'”;该运算符是正则表达式的缩写,若数据字符中含有数字时,返回的结果是true,反之返回的结果是false。

在mysql中,是否需要commit取决于存储引擎:1、若是不支持事务的存储引擎,如myisam,则不需要使用commit;2、若是支持事务的存储引擎,如innodb,则需要知道事务是否自动提交,因此需要使用commit。


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