linux下在mysql数据库中创建和删除用户
第一步:进入mysql mysql -uroot msyql -p 回车输入root用户的密码(安装mysql时自己指定的) 创建一个test用户,密码位test,“%“代表联网中的所有用户都能用test用户名访问数据库(所有数据库中的所有表); grant all on *.* to 'test'@'%' identified b
第一步:进入mysql
mysql -uroot msyql -p 回车输入root用户的密码(安装mysql时自己指定的)
创建一个test用户,密码位test,“%“代表联网中的所有用户都能用test用户名访问数据库(所有数据库中的所有表);
grant all on *.* to 'test'@'%' identified by 'test';
并将/etc/mysql/mysql.cnf中的bind-address一行注释
访问a_db中的所有表,用如下语句实现
grant all on a_db.* to 'test'@'%' identified by 'test';
限制权限,限制test用户只能查询a_db中的所有表
grant select on a_db.* to 'test'@'%' identified by 'test';
查看mysql中的所有数据库用户
select distinct concat('User: ''',user,'''@''',host,''';') as query from mysql.user;
删除test用户
delete from user where User='test' and Host='%';
flush privileges;
删除数据库和数据表
drop database 数据库名;
drop table 数据表名;

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics











In MySQL, the function of foreign keys is to establish the relationship between tables and ensure the consistency and integrity of the data. Foreign keys maintain the effectiveness of data through reference integrity checks and cascading operations. Pay attention to performance optimization and avoid common errors when using them.

The main difference between MySQL and MariaDB is performance, functionality and license: 1. MySQL is developed by Oracle, and MariaDB is its fork. 2. MariaDB may perform better in high load environments. 3.MariaDB provides more storage engines and functions. 4.MySQL adopts a dual license, and MariaDB is completely open source. The existing infrastructure, performance requirements, functional requirements and license costs should be taken into account when choosing.

SQL is a standard language for managing relational databases, while MySQL is a database management system that uses SQL. SQL defines ways to interact with a database, including CRUD operations, while MySQL implements the SQL standard and provides additional features such as stored procedures and triggers.

Redis is a memory data structure storage system, mainly used as a database, cache and message broker. Its core features include single-threaded model, I/O multiplexing, persistence mechanism, replication and clustering functions. Redis is commonly used in practical applications for caching, session storage, and message queues. It can significantly improve its performance by selecting the right data structure, using pipelines and transactions, and monitoring and tuning.

In Linux, file and directory management uses ls, cd, mkdir, rm, cp, mv commands, and permission management uses chmod, chown, and chgrp commands. 1. File and directory management commands such as ls-l list detailed information, mkdir-p recursively create directories. 2. Permission management commands such as chmod755file set file permissions, chownuserfile changes file owner, and chgrpgroupfile changes file group. These commands are based on file system structure and user and group systems, and operate and control through system calls and metadata.

MongoDB's future is full of possibilities: 1. The development of cloud-native databases, 2. The fields of artificial intelligence and big data are focused, 3. The improvement of security and compliance. MongoDB continues to advance and make breakthroughs in technological innovation, market position and future development direction.

macOSandLinuxbothofferuniquestrengths:macOSprovidesauser-friendlyexperiencewithexcellenthardwareintegration,whileLinuxexcelsinflexibilityandcommunitysupport.macOS,developedbyApple,isknownforitssleekinterfaceandecosystemintegration,whereasLinux,beingo

Handling high DPI display in C can be achieved through the following steps: 1) Understand DPI and scaling, use the operating system API to obtain DPI information and adjust the graphics output; 2) Handle cross-platform compatibility, use cross-platform graphics libraries such as SDL or Qt; 3) Perform performance optimization, improve performance through cache, hardware acceleration, and dynamic adjustment of the details level; 4) Solve common problems, such as blurred text and interface elements are too small, and solve by correctly applying DPI scaling.
