sql基础

1、mysql基础命令

查看数据库：show databases;
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查看数据库中的表：show tables;
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显示表结构：description或者DESC users;
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查看记录：select user,password from users where user_id=1;

2、 information_schema

• TABLE_SCHEMA：数据库名

• TABLE_NAME：表名

 

 

2.1 TABLES表

 

显示所有信息：select * from information_schema ;
查询数据库：select DISTINCT TABLE_SCHEMA from information_schema.TABLES ;
查询数据库和数据表：select TABLE_SCHEMA ,GROUP_CONCAT(TABLE_NAME) from information_schema.tables group by TABLE_SCHEMA \G
显示数据表：select TABLE_NAME from information_schema.tables where TABLE_SCHEMA='dvwa' ;

2.2 columns表

column_name：字段名

查询所有列：select * from information_schema.columns\G
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查询某个库的某个表：select column_name  from information_schema.columns where TABLE_SCHEMA ='dvwa' and TABLE_NAME ='users';
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查询某个表：select column_name  from information_schema.columns where TABLE_NAME ='SCHEMA_PRIVILEGES';

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显示数据库的信息：select first_name,last_name  from users where user_id =1 union select version(),database()
select first_name,last_name  from users where user_id =1 union select user(),database();
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