mysql基本语句

• 数据库

创建库
    create database uplooking;

删除库
    drop database uplooking;

修改库
     alter database uplooking character set = utf8 

     alter database uplooking collate=utf8_general_ci

• 表

创建表
    create table home (id int not null primary key auto_increment, name varchar(250) not null, class varchar(250) not null);

查看表结构
    desc home;

修改表
    添加字段：alter table home add gender enum('f','m');
    删除字段：alter table home drop gender;
    修改字段：
        alter table home change name username varchar(100) after id;
        alter table home modify username varchar(100) first;
删除表
    drop table home;

前言：insert, delete, update, select

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• insert

insert into home (class,username) values ('ops', '运维开发'), ('opsdev', '运维开发'), ('开发', 'java开发');

• update

update home set class = '开发部门' where id = 1;

• delete

delete from home where class = '开发';

• select

查询表上的所有的数据
    select * from home;

查询部分数据
    select id,class from home;
    # 还可以取个别名
    select id as num,class from home;

使用where子句过滤
    # 可以使用的算数运算符：>, < , >=, <=, ==, != 
    # 可以使用连接词：and , or
    select * from home where id >= 2;
    select * from home where id <= 2 and id >1;
    select * from home where id between 1 and 2;

    # 可以使用like做模糊匹配（%：表示任意长度的字符，_：表示任意单个字符）
    select * from home where class like 'ops%';

    # 可以使用null对值进行判断
    select * from home where id is not null; 
    select * from home where id is null; 

使用order指定排序（默认是asc,升序排列）
     select * from home order by id desc;

前言：grant revoke

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• grant

1：先创建用户，再授权
create user yhy@'172.16.19.%' identified by '123456';
grant all on *.* to yhy@'172.16.19.%';
flush privileges;


2：创建用户的同时给用户授权
grant all on *.* to yhy@'172.16.19.%' identified by '123456';
flush privileges;

3：给用户授予某些权限
show grants for yhy@'172.16.19.%';

• revoke

revoke select ON *.* from yhy@'172.16.19.%';
flush privileges;

• 查看用户的权限

show grants for yhy@'172.16.19.%';

• 删除用户

delete from mysql.user where user = "yhy";
flush privileges;