- PDO(PHP DATA OBJECT),PHP支持几乎市面上所有的数据库，但抽象度不免访问接口不够统一，所以PDO出现了，它提供了一个通用接口访问多种数据库，即抽象的数据库模型支持连接多种数据库，PDO扩展只是一个抽象层，本身不能实现数据库操作，必须使用一个特定的数据库PDO驱动访问数据库，从语法上PDO更接近MySQLi,之前学过PDO就不在这贴笔记了，只写一引起之前没学过的。
- PDO效率：PDO的CRUD效率比MYSQL直连大概低5%-15%，并且方差大于MYSQL直连，如果项目对运行效率要求严格则应MYSQL或MYSQLI，PDO负载方面，PDO开启长连接后负载高于MYSQL且比较稳定，PDO连接MYSQL/ORACLE速度比直连有优势。
- 数据库应用优化基本语句优化10个原则：1.尽量避免在列上进行运算，这样会导致索引失败，select * from t where YEAR(d) >= 2011 优化为select * from t where d >= '2011-01-01'2.使用JOIN时，应用用小结果集驱动大结果集。同时把复杂的JOIN查询拆分成多个Query，因为JOIN多个表时可能导致更多的锁定和堵塞。3.注意LIKE模糊查询的使用，避免%%4.仅列出需要查询的字段，这对速度不会有明显影响，主要考虑内在节省。5.使用指插入语句节省交互6.limit的基数比较大时使用between，between限定比limit快，所以在海量数据访问时建议用between或是where替换掉limit，但是between的缺陷是如果中间有断行或部分不读取的情况则总读取的数量会少于预计数量！在取比较后面的数据时，通过desc方式把数据反射查找，以减少对前段数据的扫描，让limit的基数越小越好。7.不要使用rand函数获取多条随机记录8.避免使用NULL9.不要使用count(id)而应该是count(*)10.不要做无谓的排序操作而尽可能在索引中完成排序
- 索引与性能分析分析执行效率：set @@profiling=1;select * from tableName where condition;show profiles;或者show profile for query n;得到某次查询的详细性能报告以定位性能瓶颈，同一条语句的第二次查询明显比第一次查询要快是因为SQL缓存的结果。MYSQL索引建立和使用基本原则：合理设计和使用索引在关键字段的索引上，建与不建索引查询速度相差近100倍差的索引和没有索引效果一样维护索引需要成本，不是越多越好每个表索引应在5个以下，就合理利用部分索引和联合索引不在结果集中的结果单一的列上建索引，比如性别只有0和1两种在这个字段上建索引并不会有太多帮助建索引的字段结果集最好分布均匀，或者符合正太分布
- 服务器和配置的优化MYSQL常用的引擎对比-------------MyISAM-------Memory---------------InnoDB用途----------快读--------内存数据------------完整的事务支持锁------------全表锁定----全表锁定------------多种隔离级别的行锁持久性--------基于表恢复---无磁盘IO无可持久性---基于日志的恢复事务支持------不支持-------不支持--------------支持索引类型---B-tree/FullText/R-tree---Hash/B-tree---Hash/B-tree
PHP: An Introduction to the Server-Side Scripting LanguageApr 16, 2025 am 12:18 AMPHP is a server-side scripting language used for dynamic web development and server-side applications. 1.PHP is an interpreted language that does not require compilation and is suitable for rapid development. 2. PHP code is embedded in HTML, making it easy to develop web pages. 3. PHP processes server-side logic, generates HTML output, and supports user interaction and data processing. 4. PHP can interact with the database, process form submission, and execute server-side tasks.
PHP and the Web: Exploring its Long-Term ImpactApr 16, 2025 am 12:17 AMPHP has shaped the network over the past few decades and will continue to play an important role in web development. 1) PHP originated in 1994 and has become the first choice for developers due to its ease of use and seamless integration with MySQL. 2) Its core functions include generating dynamic content and integrating with the database, allowing the website to be updated in real time and displayed in personalized manner. 3) The wide application and ecosystem of PHP have driven its long-term impact, but it also faces version updates and security challenges. 4) Performance improvements in recent years, such as the release of PHP7, enable it to compete with modern languages. 5) In the future, PHP needs to deal with new challenges such as containerization and microservices, but its flexibility and active community make it adaptable.
Why Use PHP? Advantages and Benefits ExplainedApr 16, 2025 am 12:16 AMThe core benefits of PHP include ease of learning, strong web development support, rich libraries and frameworks, high performance and scalability, cross-platform compatibility, and cost-effectiveness. 1) Easy to learn and use, suitable for beginners; 2) Good integration with web servers and supports multiple databases; 3) Have powerful frameworks such as Laravel; 4) High performance can be achieved through optimization; 5) Support multiple operating systems; 6) Open source to reduce development costs.
Debunking the Myths: Is PHP Really a Dead Language?Apr 16, 2025 am 12:15 AMPHP is not dead. 1) The PHP community actively solves performance and security issues, and PHP7.x improves performance. 2) PHP is suitable for modern web development and is widely used in large websites. 3) PHP is easy to learn and the server performs well, but the type system is not as strict as static languages. 4) PHP is still important in the fields of content management and e-commerce, and the ecosystem continues to evolve. 5) Optimize performance through OPcache and APC, and use OOP and design patterns to improve code quality.
The PHP vs. Python Debate: Which is Better?Apr 16, 2025 am 12:03 AMPHP and Python have their own advantages and disadvantages, and the choice depends on the project requirements. 1) PHP is suitable for web development, easy to learn, rich community resources, but the syntax is not modern enough, and performance and security need to be paid attention to. 2) Python is suitable for data science and machine learning, with concise syntax and easy to learn, but there are bottlenecks in execution speed and memory management.
PHP's Purpose: Building Dynamic WebsitesApr 15, 2025 am 12:18 AMPHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.
PHP: Handling Databases and Server-Side LogicApr 15, 2025 am 12:15 AMPHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.
How do you prevent SQL Injection in PHP? (Prepared statements, PDO)Apr 15, 2025 am 12:15 AMUsing preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.
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