0. 删除系统多余账号
 use mysql;
 select user,host from mysql.user;
 delete from user where user=‘‘;
 flush privileges;

 mysql创建账号:
 mysqladmin -u root password ‘123456‘

以demo库test库分别demo_1和test_1表为例:
  create database demo;
 

  create table demo_1(id int);
  insert into demo_1(id) values(1),(2),(3);
 

  create database test;
  create table test_1(id int);
  insert into test_1(id) values(1),(2),(3);
 

   create table test_2(id int);
   insert into test_2(id) values(1),(2),(3);

1. 授权所有库
   创建新用户并授权,且密码为空: grant all on *.* to test@‘localhost‘

   创建新用户并授权,且设密码: grant all on *.* to test@‘localhost‘ identified by ‘123456‘;
                   或  grant select, insert, update, delete on *.* to test@‘localhost‘

   刷新权限: flush privileges;

   查看权限: show grants for test@‘localhost‘;
               GRANT ALL PRIVILEGES ON *.* TO ‘test‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘ 

   测试权限(可以): mysql -utest -p123456 -e ‘select * from demo.demo_1‘;  

 1.1 收回权限
     收回权限: revoke all on *.* from test@‘localhost‘;

     刷新权限: flush privileges;

     查看权限: show grants for test@‘localhost‘;
                GRANT USAGE ON *.* TO ‘test‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘

     测试权限(不可以): mysql -utest -p123456 -e ‘select * from demo.demo_1‘;
            ERROR 1142 (42000) at line 1: SELECT command denied to user ‘test‘@‘localhost‘ for table ‘demo_1‘
     
2. 授权指定库(1个或多个库)
     grant all on test.* to test@‘localhost‘;
     grant all on demo.* to test@‘localhost‘;    
    注意：不能一次对指定的多个库进行授权，只能一个一个授权：grant all on test.*,demo.* to test@‘localhost‘;

    查看权限: show grants for test@‘localhost‘;
            GRANT USAGE ON *.* TO ‘test‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘

            GRANT ALL PRIVILEGES ON `test`.* TO ‘test‘@‘localhost‘
            GRANT ALL PRIVILEGES ON `demo`.* TO ‘test‘@‘localhost‘

     测试权限(可以): mysql -utest -p123456 -e ‘select * from demo.demo_1‘; 

 2.1 收回权限
        revoke all on test.* from test@‘localhost‘;
        revoke all on demo.* from test@‘localhost‘;
        flush privileges;

      测试权限：mysql -utest -p123456 -e ‘select * from demo.demo_1‘;
                ERROR 1142 (42000) at line 1: SELECT command denied to user ‘test‘@‘localhost‘ for table ‘demo_1‘
3. 授权指定库(1张或多张表)
      授权: grant all on test.test_2 to test@‘localhost‘;
      刷新权限: flush privileges;
      查看权限: show grants for test@‘localhost‘;
               GRANT USAGE ON *.* TO ‘test‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘
               GRANT ALL PRIVILEGES ON `test`.`test_2` TO ‘test‘@‘localhost‘
      测试权限: mysql -utest -p123456 -e ‘select * from test.test_1‘;
                   ERROR 1142 (42000) at line 1: SELECT command denied to user ‘test‘@‘localhost‘ for table ‘test_1‘
              mysql -utest -p123456 -e ‘select * from test.test_2‘; 查询有东西

      注意：授权一个不存在的表居然也可以成功，还可以查看出权限。
 3.1 收回权限
         revoke all on test.test_2 from test@‘localhost‘;
         flush privileges;
         
4. 隐藏库不让授权
   information_schema  该库存储了mysql一些元数据，如数据库名或表名，列的数据类型，或访问权限等
   mysql

5. 将ip整成域名访问数据库
   192.168.11.17 www.db.com
   navcat中就可以直接填写域名，指定端口，需要注意host是控制访问的权限 %/192.168.11.%/192.168.11.18/等等

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