查看Oracle数据库状态 无 show sgaset wrap offset linesize 400-- 查看正在运行的后台进程select * from v$bgprocess;select * from v$bgprocess where paddr'00';--查看数据库的物理组成:文件情况select * from v$controlfile;select * from v$datafile;se
查看Oracle数据库状态show sga set wrap off set linesize 400 -- 查看正在运行的后台进程 select * from v$bgprocess; select * from v$bgprocess where paddr<>'00'; --查看数据库的物理组成:文件情况 select * from v$controlfile; select * from v$datafile; select * from v$logfile; --查看实例内存情况 show parameter sga show parameter shared show parameter db_cache show parameter log alter system set db_cache_size=64m; //可以动态修改sga中内存区的大小,但是不能超过sga的最大内存 select * from dept; --表空间管理 CREATE TABLESPACE tbs2 DATAFILE 'D:\oracle\oradata\APTECH\tbs2_01.dbf' SIZE 50M; conn sys/admin as sysdba(重启数据库必须以sys用户登陆) shutdown immediate(关闭数据库) 启动数据库的三个步骤: startup nomount (启动实例) alter database mount;(装载数据库,读取控制文件) alter database open;(打开数据库,对数据文件,日志文件进行一致性校验) --用户管理 -- Create the user CREATE USER MARTIN IDENTIFIED BY martinpwd DEFAULT TABLESPACE USERS TEMPORARY TABLESPACE TEMP; -- Grant role privileges GRANT CONNECT TO MARTIN; GRANT RESOURCE TO MARTIN; -- 如果不使用 CONNECT 角色,则需要逐个赋予用户权限 GRANT CREATE SESSION TO MARTIN; GRANT CREATE TABLE TO MARTIN; GRANT CREATE VIEW TO MARTIN; GRANT CREATE SEQUENCE TO MARTIN; GRANT CREATE SEQUENCE TO MARTIN; GRANT SELECT ON TEST TO MARTIN; GRANT ALL ON TEST TO MARTIN; -- 授予用户使用表空间 USERS 的权限 ALTER USER MARTIN QUOTA UNLIMITED ON USERS; --修改用户密码 ALTER USER MARTIN IDENTIFIED BY martinpass; --修改自己的密码 在sql*plus中直接输入password命令即可 --删除用户 DROP USER MARTIN CASCADE; -- 查看用户 MARTIN 的信息 select USERNAME,USER_ID,DEFAULT_TABLESPACE,TEMPORARY_TABLESPACE from dba_users where username = 'MARTIN';

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

MySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.

MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA


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