浅谈MySql的存储引擎(表类型)
通常意义上,数据库也就是数据的集合,具体到计算机上数据库可以是存储器上一些文件的集合或者一些内存数据的集合
这种引擎是mysql最早提供的。这种引擎又可以分为静态MyISAM、动态MyISAM 和压缩MyISAM三种:
这种类型是MyISAM类型的一种变种。合并表是将几个相同的MyISAM表合并为一个虚表。常应用于日志和数据仓库。
3 InnoDB:
4 memory(heap):
5 archive:
当然MySql支持的表类型不止上面几种。
下面我们介绍一下如何查看和设置数据表类型。
1 查看数据库可以支持的存储引擎
用show engines; 命令可以显示当前数据库支持的存储引擎情况,如图1所示:
图1 数据库的存储引擎
由上图可见当前系统的默认数据表类型是MyISAM。当然,我们可以通过修改数据库配置文件中的选项,设定默认表类型。
2 查看表的结构等信息的若干命令
要查看表的定义结构等信息可以使用以下几种命令:
2.1Desc[ribe]
例如,查看表t1的结构,可得下图。
图2:查看表t1的结构
2.2 Show create table tablename; //显示表的创建语句
同上查询表t1,得下图:
图3 显示创建表t1的语句
2.3 show table status like ‘tablename'\G显示表的当前状态值
同上查询表t1,得下图:
图4 显示表t1 的当前状态值
综上可见,后两种方式都可以帮助我们查看某一表的存储引擎类型(图中已用红色方框标出)。
3 设置或修改表的存储引擎
3.1创建数据库表时设置存储存储引擎的基本语法是:
图6 显示表t1 的当前状态值
3.2修改存储引擎,可以用命令Alter table tableName engine =engineName
图7 修改表user的存储引擎
图8 显示表user修改后的状态值

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