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1.MySQL的用户管理
MySQL的用户信息都保存在数据库mysql的user表中,因此MySQL的用户操作实际上就是对mysql.user表的增删查改的操作,下图中展示了mysql.user的表结构:
从图中可以看到,在该表中可以设置用户的所有信息,包括用户名,密码,权限等等。 Notice:password字段是通过PASSWORD('')函数生成的。 除了修改user表的方式来操作MySQL用户外,MySQL有一些额外的命令用于创建或删除MySQL用户。 2.创建用户2.1.CREATE USER创建无权限用户语法:CREATE USER user [IDENTIFIED BY [PASSWORD] 'password'][, user [IDENTIFIED BY [PASSWORD] 'password']] ... 示例:create user test@localhost identified by 'test';//创建一个用户名为test,密码为test的用户,该用户没有任何权限 2.2.GRANT方式创建带权限用户语法:GRANT [ALL | [SELECT,DELETE...]] PRIVILEGES ON {databasename|*}.{tablename|*}... TO username IDENTIFIED BY password; 示例:GRANT ALL PRIVILEGES ON *.* TO test@% IDENTIFIED BY 'test'; 3.删除用户语法:DROP USER username;//username指的是带host的username,即test@localhost,如果不指定host,host就为%. 示例:DROP USER test@localhost; 4.MySQL权限说明4.1查看某个用户的权限mysql> show grants for root@localhost; 4.2各权限解释权限 列 说明 CREATE Create_priv 创建数据库和表 DROP Drop_priv 抛弃(删除)数据库和表 GRANT OPTION Grant_priv 数据库、表或保存的程序 REFERENCES References_priv 未使用 ALTER Alter_priv 修改表和索引 DELETE Delete_priv 表 INDEX Index_priv 创建或抛弃索引 INSERT Insert_priv 向表中插入新行 SELECT Select_priv 检索表中的记录 UPDATE Update_priv 修改现存表记录 CREATE VIEW Create_view_priv 视图 SHOW VIEW Show_view_priv 视图 ALTER ROUTINE Alter_routine_priv 保存的程序 CREATE ROUTINE Create_routine_priv 保存的程序 EXECUTE Execute_priv 保存的程序 FILE File_priv 读或写服务器上的文件 CREATE TEMPORARY TABLES Create_tmp_table_priv 服务器管理 LOCK TABLES Lock_tables_priv 服务器管理 CREATE USER Create_user_priv 服务器管理 PROCESS Process_priv 查看服务器中执行的线程信息或杀死线程 RELOAD Reload_priv 重载授权表或清空日志、主机缓存或表缓存 REPLICATION CLIENT Repl_client_priv 服务器管理 REPLICATION SLAVE Repl_slave_priv 服务器管理 SHOW DATABASES Show_db_priv 服务器管理 SHUTDOWN Shutdown_priv 关闭服务器 SUPER Super_priv 服务器管理 作者 sin90lzc bitsCN.com

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

MySQL is suitable for small and large enterprises. 1) Small businesses can use MySQL for basic data management, such as storing customer information. 2) Large enterprises can use MySQL to process massive data and complex business logic to optimize query performance and transaction processing.

InnoDB effectively prevents phantom reading through Next-KeyLocking mechanism. 1) Next-KeyLocking combines row lock and gap lock to lock records and their gaps to prevent new records from being inserted. 2) In practical applications, by optimizing query and adjusting isolation levels, lock competition can be reduced and concurrency performance can be improved.

MySQL is not a programming language, but its query language SQL has the characteristics of a programming language: 1. SQL supports conditional judgment, loops and variable operations; 2. Through stored procedures, triggers and functions, users can perform complex logical operations in the database.

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL is an open source relational database management system suitable for data storage, management, query and security. 1. It supports a variety of operating systems and is widely used in Web applications and other fields. 2. Through the client-server architecture and different storage engines, MySQL processes data efficiently. 3. Basic usage includes creating databases and tables, inserting, querying and updating data. 4. Advanced usage involves complex queries and stored procedures. 5. Common errors can be debugged through the EXPLAIN statement. 6. Performance optimization includes the rational use of indexes and optimized query statements.

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

InnoDB's lock mechanisms include shared locks, exclusive locks, intention locks, record locks, gap locks and next key locks. 1. Shared lock allows transactions to read data without preventing other transactions from reading. 2. Exclusive lock prevents other transactions from reading and modifying data. 3. Intention lock optimizes lock efficiency. 4. Record lock lock index record. 5. Gap lock locks index recording gap. 6. The next key lock is a combination of record lock and gap lock to ensure data consistency.


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