[MySQL] 获取元数据的步骤
[MySQL] 获取元数据的方法 MySQL提供了以下三种方法用于获取数据库对象的元数据: 1)show语句 2)从INFORMATION_SCHEMA数据库里查询相关表 3)命令行程序,如mysqlshow, mysqldump 用SHOW语句获取元数据 MySQL用show语句获取元数据是最常用的方法,下面提供
[MySQL] 获取元数据的方法MySQL提供了以下三种方法用于获取数据库对象的元数据:
1)show语句
2)从INFORMATION_SCHEMA数据库里查询相关表
3)命令行程序,如mysqlshow, mysqldump
用SHOW语句获取元数据
MySQL用show语句获取元数据是最常用的方法,下面提供了几种典型用法:
show databases; --列出所有数据库 show create database db_name; --查看数据库的DDL show tables; --列出默认数据库的所有表 show tables from db_name; --列出指定数据库的所有表 show table status; --查看表的描述性信息 show table status from db_name; show create table tbl_name; --查看表的DDL show columns from tbl_name; --查看列信息 show index from tbl_name; --查看索引信息
show columns from domaininfo like 's%';
show columns from domaininfo where field='sysdomain';
注:desc tbl_name和explain tbl_name的效果和show columns from tbl_name一致。
从INFORMATION_SCHEMA数据库里查询相关表
INFORMATION_SCHEMA是MySQL自带的一个系统数据库,它里面存储了所有的元数据,通过select里面的相关表就可以获取你想要的元数据。和show语句相比,它比较麻烦,但它的好处是标准的SQL语句,更具有可移植性,且更灵活,可以通过各种表达式获取你真正需要的信息。
从命令行获取元数据
前面两种方法都必须得在MySQL命令行里执行,而mysqlshow和mysqldump提供了从OS命令行获取元数据库的方法,如:mysqlshow --列出所有数据库 mysqlshow db_name --列出给定数据库的所有表 mysqlshow db_name tbl_name --列出给定数据库表的所有列 mysqlshow --keys db_name tbl_name --列出索引信息 mysqlshow --status db_name --列出数据库的描述性信息
mysqldump --no-data db_name [tbl_name] ...

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