数据库身份认证比较好理解,就是数据库用户口令以加密的方式保存在数据库内部,当用户连接数据库时必须输入用户名和密码,通过数
数据库身份认证
数据库身份认证比较好理解,就是数据库用户口令以加密的方式保存在数据库内部,当用户连接数据库时必须输入用户名和密码,通过数据库认证后才可以登录到数据库。例如,创建一个数据库认证的用户,语句为:
SQL> create user hxy4 identified bysys123; // 通过by这个关键字来确定认证方式为数据库身份认证
User created.
为此,数据库必须处于打开状态
外部身份认证)
当用户试图建立与数据库的连接时,数据库不会要求用户输入口令和用户名
——如果使用外部身份验证创建用户账户,Oracle 会将身份验证委托给外部服务。它不会提示输入口令。如果为启用 Advaned Security 选项,则唯一可以使用得外部身份验证方形式是操作系统身份验证。此技术使用与操作系统用户账户同样的名称创建 Oracle 用户账户,,但在前面加OS_AUTHENT_PREFIX 实例参数指定的字符串。此参数默认为 OPS$ 字符串。可以用下列语句查询:
SQL> show parameter os_authent_prefix NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ os_authent_prefix string ops$ SQL> 或者: SQL VALUE -------------------------------------------------------------------------------- ops$
创建外部操作系统身份验证的用户很简单,假如有一个操作系统用户名为 dragon,则:
对于 LINUX 系统: create user ops$dragon identified externally; 对于 WINDOWS 系统,假如登陆 ID 是 Dragon,域名是 MIS: create user "OPS$MIS\DRAGON" identified externally;
创建好用户后,以 dragon 身份登录到操作系统,然后在直接输入:sqlplus / 进行登录并连接到数据库。

MySQLdiffersfromotherSQLdialectsinsyntaxforLIMIT,auto-increment,stringcomparison,subqueries,andperformanceanalysis.1)MySQLusesLIMIT,whileSQLServerusesTOPandOracleusesROWNUM.2)MySQL'sAUTO_INCREMENTcontrastswithPostgreSQL'sSERIALandOracle'ssequenceandt

MySQL partitioning improves performance and simplifies maintenance. 1) Divide large tables into small pieces by specific criteria (such as date ranges), 2) physically divide data into independent files, 3) MySQL can focus on related partitions when querying, 4) Query optimizer can skip unrelated partitions, 5) Choosing the right partition strategy and maintaining it regularly is key.

How to grant and revoke permissions in MySQL? 1. Use the GRANT statement to grant permissions, such as GRANTALLPRIVILEGESONdatabase_name.TO'username'@'host'; 2. Use the REVOKE statement to revoke permissions, such as REVOKEALLPRIVILEGESONdatabase_name.FROM'username'@'host' to ensure timely communication of permission changes.

InnoDB is suitable for applications that require transaction support and high concurrency, while MyISAM is suitable for applications that require more reads and less writes. 1.InnoDB supports transaction and bank-level locks, suitable for e-commerce and banking systems. 2.MyISAM provides fast read and indexing, suitable for blogging and content management systems.

There are four main JOIN types in MySQL: INNERJOIN, LEFTJOIN, RIGHTJOIN and FULLOUTERJOIN. 1.INNERJOIN returns all rows in the two tables that meet the JOIN conditions. 2.LEFTJOIN returns all rows in the left table, even if there are no matching rows in the right table. 3. RIGHTJOIN is contrary to LEFTJOIN and returns all rows in the right table. 4.FULLOUTERJOIN returns all rows in the two tables that meet or do not meet JOIN conditions.

MySQLoffersvariousstorageengines,eachsuitedfordifferentusecases:1)InnoDBisidealforapplicationsneedingACIDcomplianceandhighconcurrency,supportingtransactionsandforeignkeys.2)MyISAMisbestforread-heavyworkloads,lackingtransactionsupport.3)Memoryengineis

Common security vulnerabilities in MySQL include SQL injection, weak passwords, improper permission configuration, and unupdated software. 1. SQL injection can be prevented by using preprocessing statements. 2. Weak passwords can be avoided by forcibly using strong password strategies. 3. Improper permission configuration can be resolved through regular review and adjustment of user permissions. 4. Unupdated software can be patched by regularly checking and updating the MySQL version.

Identifying slow queries in MySQL can be achieved by enabling slow query logs and setting thresholds. 1. Enable slow query logs and set thresholds. 2. View and analyze slow query log files, and use tools such as mysqldumpslow or pt-query-digest for in-depth analysis. 3. Optimizing slow queries can be achieved through index optimization, query rewriting and avoiding the use of SELECT*.


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