The difference and usage of php database connection mysql and mysqli
Today we will talk about the difference and usage of mysql and mysqliConnecting database. In fact, mysql has been abandoned in PHP5.6 and above. , but many students are still using it. Today we will talk about the difference between mysql and mysqli connection.
1. The concepts of mysql and mysqli are related:
1. Mysql and mysqli are both function sets in PHP, and mysql database is not very relevant.
2. Before the php5 version, the mysql function of php was generally used to drive the mysql database. For example, the mysql_query() function is process-oriented. 3. After the php5 version, the mysqli function has been added. In a sense, it is an enhanced version of the mysql system function, which is more stable, efficient and secure. Corresponding to mysql_query() is mysqli_query(), which is object-oriented and uses objects to operate and drive the mysql database
2. The difference between mysql and mysqli:
1. Mysql is a non-persistent connection function. Every time mysql is connected, Open a connected process.
2. Mysqli is a permanent connection function. Running mysqli multiple times will use the same connection process, thus reducing server overhead. mysqli encapsulates some advanced operations such as transactions, and also encapsulates many available methods in the DB operation process.
3. Usage of mysql and mysqli:
1:mysql (process mode):
$conn = mysql_connect('localhost', 'user', 'password'); //连接mysql数据库 mysql_select_db('data_base'); //选择数据库 $result = mysql_query('select * from data_base');//第二个可选参数,指定打开的连接 $row = mysql_fetch_row( $result ) ) //只取一行数据 echo $row[0]; //输出第一个字段的值
PS: mysqli operates in a procedural manner. Some functions must specify resources, such as mysqli_query (resource identifier, SQL statement), and the parameter of the resource identifier is placed in front, while mysql_query (SQL statement,' The resource ID ') is optional and the default value is the last opened connection or resource.
2. mysqli (object mode):
$conn = new mysqli('localhost', 'user', 'password','data_base'); //要使用new操作符,最后一个参数是直接指定数据库 //假如构造时候不指定,那下一句需要$conn -> select_db('data_base')实现 $result = $conn -> query( 'select * from data_base' ); //执行sql语句 $row = $result -> fetch_row(); //取一行数据 echo = row[0]; //输出第一个字段的值
Using new mysqli('localhost', usenamer', 'password', 'databasename'); will report an error with the following prompt:
Fatal error: Class 'mysqli' not found in ...
Generally mysqli is not enabled because the mysqli class is not enabled by default. Under win, you need to change php.ini and remove php_mysqli.dll. Before;, mysqli must be compiled into Linux.
4. mysql_connect() and mysqli_connect()
Related recommendations:
php implements mysql (MySQL and MySQLi mode) operation class
Perfectly solve the implementation steps and error reporting of PHP installation extension mysqli
PHP connection database class based on MySQLI function
The above is the detailed content of The difference and usage of php database connection mysql and mysqli. For more information, please follow other related articles on the PHP Chinese website!

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 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.

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

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.

The key to installing MySQL elegantly is to add the official MySQL repository. The specific steps are as follows: Download the MySQL official GPG key to prevent phishing attacks. Add MySQL repository file: rpm -Uvh https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm Update yum repository cache: yum update installation MySQL: yum install mysql-server startup MySQL service: systemctl start mysqld set up booting

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.
