如果要审计数据库中的DDL操作,那么可以通过DDL触发器来实现,本节介绍一个例子,把数据库中的所有DDL操作都记录下来。本例子可以
如果要审计数据库中的DDL操作,那么可以通过DDL触发器来实现,本节介绍一个例子,把数据库中的所有DDL操作都记录下来。本例子可以在Oracle 8i或更高的版本中使用。
第一步,创建表空间和相关的日志表:
create tablespace statlog datafile '/oradata/statlog.dbf' size 200m;
create table stat$log_ddl
(
ddl_date date,
user_name varchar2(30),
ip_addr VARCHAR2(30),
obj_name VARCHAR2(50),
ddl_type VARCHAR2(30),
object_type VARCHAR2(18),
owner VARCHAR2(30),
SQL_TEXT VARCHAR2(1000)
) TABLESPACE STATLOG;
第二步,创建数据库级的DDL触发器,把所有的DDL操作都记录下来
CREATE OR REPLACE TRIGGER DDL_audit AFTER CREATE OR ALTER OR DROP OR TRUNCATE OR
GRANT OR REVOKE OR RENAME
on DATABASE
declare
ipaddr varchar2(20);
STEXT VARCHAR2(1000);
BEGIN
begin
select sys_context('USERENV', 'IP_ADDRESS') into ipaddr FROM dual;
exception when others then
ipaddr:='-';
end;
begin
select SQL_TEXT INTO STEXT FROM v$open_cursor WHERE UPPER(sql_text) LIKE 'ALTER%';
exception when others then
STEXT:='-';
end;
insert into sys.stat$log_DDL values
(sysdate,
user,
nvl (ipaddr,'-'),
NVL(ora_dict_obj_name,'-'),
NVL(ORA_SYSEVENT,'-'),
NVL(ora_dict_obj_type,'-'),
NVL(ora_dict_obj_owner,'-'),
STEXT
);
exception when others then
null;
end;
/

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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