MySQL操作

Posted 2020-11-18 argor

1.SQL　　　　　　　　

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1.SQL    

• DDL：create、alter、drop
• DCL：grant、revoke
• DML：update、insert、delete
• DQL：select

 

1.1.DDL

创建数据库

• 语法：create database dbName [character set charsetName [collate colName]]

mysql> create database db_users character set binary;
mysql> create database db_college;

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 修改数据库

mysql> alter database db_users character set utf8;

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 删除数据库

mysql> drop database db_users;

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数据类型对照

Java	MySQL
byte/short/int/long	tinyint/smallint/int/bigint
float/double	float/double
boolean	bit
char/String	char/varchar
Date	date/time/datetime/timestamp
File	blog/text

 

创建表

mysql> create table t_student(
    ->  id int primary key auto_increment,
    ->  name nchar(30) not null,
    ->  gender char(1),
    ->  score double,
    ->  state char(1) default 1,
    ->  idcard int(18) unique
    ->  );

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 修改表结构

• 增、删、改 表结构，分别用到关键字：add、drop、change、modify

增加列、修改列定义、修改列名称、删除列

mysql> alter table t_student add descStu varchar(150);
mysql> alter table t_student modify descStu varchar(350);
mysql> alter table t_student change descStu descption varchar(350);
mysql> alter table t_student drop descption;

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表的重命名、修改字符集

mysql> rename table t_student to t_stuItheima;
mysql> alter table t_stuitheima character set utf8;

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1.2.DML

修改元组属性、删除元组

mysql> update user set password=password("admin") where host="::1" and user="root";
mysql> delete from user where user is null;

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插入数据

mysql> insert into t_student values(null, "maqi",null,234.234,null,2342342);
mysql> insert into t_student (id,name,gender,score,state,idcard) values(null, "maqi",null,234.234,null,2342342);

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1.3.备库

 备库时，直接指定库名。还原数据时，如果把库都删除了，须另外创建。

C:UsersAdministratorDesktop>mysqldump -uroot test > test.sql

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mysql> source test.sql;
C:UsersAdministratorDesktop>mysqldump -uroot test < test.sql

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中括号，表示输入、输出 重定向。

 

 

 

 

 

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