PHP查询数据有关问题
PHP查询数据问题
数据库用的是MYSQL5.5
我系统里有不少表需要关联,如微博的。
一条博文可能有好几个表关联起来,如用户表,等其它表。
问题:
服务器有memcache+apache+mysql5.5
展示博文时,因每条博文有如图片,音频,视频,等等不少关联,是用一条SQL关联出所有数据,还是先查出所有博文,再循环根据博文ID查询出其它关联数据,。
如要显示10条博文,那就要去查询10次数据库,(SQL简单,但查询数据库次数多)。
如果用一条关联查询,一条数据库即查查出,(SQL复杂。)
请问使用哪种最优
------解决方案--------------------
请使用 Cache ~
------解决方案--------------------
用left join on 速度还可以
------解决方案--------------------
我的观点:如果你发现join your table存在性能问题了,你就该放弃join了。换言之,如果还没有存心瓶颈(短期内也不会出现瓶颈)那么你可以继续join。
nosql的观点在DB不是着重业务处理,而是数据持久存储。解放DB的业务负担将极大改善DB的性能。
------解决方案--------------------
建议用程序来处理,数据库只是用来存储数据的,过于复杂的SQl不适合,数据量大的话,程序处理是最快的
------解决方案--------------------
个人感觉查询速度很大一部分出现在SQL语句上,用join完全可以,但要注意where条件,例如一下子可以过滤掉很多信息的where条件要放在所有where条件的最前面,再一个就是如果作为你查询条件的某个数据库字段如果可以作为唯一约束,主键约束等一定要在数据库中建立约束,楼主不信可以做个实验~查询所用时间是数量级上的变化,很可观的!希望能对你有所帮助
------解决方案--------------------
最好一个表一个表的查询,尽量避免使用join查询和子查询。
------解决方案--------------------
如果是泛泛的理论的讨论,那怎么弄都不为过
若已经落实到具体的表中了,那么建议使用视图
将每次都需要展示的字段加入到视图中就可以了
实际的查询是对视图进行的
------解决方案--------------------
如果是泛泛的理论的讨论,那怎么弄都不为过
若已经落实到具体的表中了,那么建议使用视图
将每次都需要展示的字段加入到视图中就可以了
实际的查询是对视图进行的

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

Apache connects to a database requires the following steps: Install the database driver. Configure the web.xml file to create a connection pool. Create a JDBC data source and specify the connection settings. Use the JDBC API to access the database from Java code, including getting connections, creating statements, binding parameters, executing queries or updates, and processing results.

The process of starting MySQL in Docker consists of the following steps: Pull the MySQL image to create and start the container, set the root user password, and map the port verification connection Create the database and the user grants all permissions to the database

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.

Laravel is a PHP framework for easy building of web applications. It provides a range of powerful features including: Installation: Install the Laravel CLI globally with Composer and create applications in the project directory. Routing: Define the relationship between the URL and the handler in routes/web.php. View: Create a view in resources/views to render the application's interface. Database Integration: Provides out-of-the-box integration with databases such as MySQL and uses migration to create and modify tables. Model and Controller: The model represents the database entity and the controller processes HTTP requests.

Installing MySQL on CentOS involves the following steps: Adding the appropriate MySQL yum source. Execute the yum install mysql-server command to install the MySQL server. Use the mysql_secure_installation command to make security settings, such as setting the root user password. Customize the MySQL configuration file as needed. Tune MySQL parameters and optimize databases for performance.
