欢迎进入Oracle社区论坛,与200万技术人员互动交流 >>进入 一。非归档模式关闭数据库的恢复 1.shutdown immediate; 关闭数据库 2.使用操作系统命令拷贝最新的备份(数据文件和控制文件,如果备份了日志文件) 3.进行不完全恢复recover database until cancel
欢迎进入Oracle社区论坛,与200万技术人员互动交流 >>进入
一。非归档模式关闭数据库的恢复
1.shutdown immediate; 关闭数据库
2.使用操作系统命令拷贝最新的备份(数据文件和控制文件,如果备份了日志文件)
3.进行不完全恢复recover database until cancel using backup;
4.重置日志打开数据库alter database open resetlogs;
二。数据文件离线或者表空间离线的恢复
SQL> create table t1 tablespace tbs_sf as select * from dba_objects; --创建测试表到指定表空间
SQL> select file_id,file_name from dba_data_files where TABLESPACE_NAME='TBS_SF'; --可以看到数据文件时26号
FILE_ID FILE_NAME
---------- --------------------------------------------------
26 /database/oradata/skyread/sf01.dbf
SQL> alter database datafile 26 offline drop; --数据文件脱机,这里是模拟故障,恢复的时候相当于从备份拷贝一个新文件回来
Database altered.
SQL> select count(*) from t1; --可见无法查看该表空间的表
select count(*) from t1
*
ERROR at line 1:
ORA-00376: file 26 cannot be read at this time
ORA-01110: data file 26: '/database/oradata/skyread/sf01.dbf'
SQL> select hxfil file_id,fhsta status,fhscn scn,fhrba_seq seq from x$kcvfh where hxfil=26;
FILE_ID STATUS SCN SEQ
---------- ---------- ---------------- ----------
26 4 122693804311 2
SQL> select GROUP#,BYTES,ARCHIVED,STATUS,SEQUENCE# from v$log; --可见红色的日志没有被覆盖,可以进行恢复
GROUP# BYTES ARC STATUS SEQUENCE#
---------- ---------- --- ---------------- ----------
1 536870912 YES INACTIVE 1
2 536870912 NO CURRENT 2
3 536870912 YES UNUSED 0
4 536870912 YES UNUSED 0
5 536870912 YES UNUSED 0
SQL> recover datafile 26; --进行恢复
Media recovery complete.
SQL> alter database datafile 26 online;
Database altered.
SQL> select count(*) from t1;
COUNT(*)
----------
50483
[1] [2]

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

The main role of MySQL in web applications is to store and manage data. 1.MySQL efficiently processes user information, product catalogs, transaction records and other data. 2. Through SQL query, developers can extract information from the database to generate dynamic content. 3.MySQL works based on the client-server model to ensure acceptable query speed.

The steps to build a MySQL database include: 1. Create a database and table, 2. Insert data, and 3. Conduct queries. First, use the CREATEDATABASE and CREATETABLE statements to create the database and table, then use the INSERTINTO statement to insert the data, and finally use the SELECT statement to query the data.

MySQL is suitable for beginners because it is easy to use and powerful. 1.MySQL is a relational database, and uses SQL for CRUD operations. 2. It is simple to install and requires the root user password to be configured. 3. Use INSERT, UPDATE, DELETE, and SELECT to perform data operations. 4. ORDERBY, WHERE and JOIN can be used for complex queries. 5. Debugging requires checking the syntax and use EXPLAIN to analyze the query. 6. Optimization suggestions include using indexes, choosing the right data type and good programming habits.


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