Backend Development
PHP Tutorial
Detailed explanation of using PDO constructor to connect to database and DSN
Detailed explanation of using PDO constructor to connect to database and DSN
Detailed explanation of using the PDO constructor to connect to the database and DSN
pdo is a newly added database abstraction layer in php5, in order to solve the problem of accessing a unified interface for different databases . It is similar to the operation of PEAR::DB class and ADODB class, but it is directly encapsulated in PHP extension and can be used freely.
In the previous article "What is PDO? In "Overview of PDO Characteristics and How to Install PDO", we introduced what PDO is, introduced the characteristics and installation of PDO, so in this article we introduce the PDO constructor to connect to the database and DSN details!
PDO constructor connects to the database
In PDO, to establish a database connection, you need to instantiate the PDO constructor. The PDO constructor The syntax format is as follows:
_construct(string $dsn[,string $username[,string $password[,array $driver_options]]])
The parameter description of the constructor is as follows:
dsn: data source name, including host name, port number and database name.
username: the username to connect to the database.
password: Password for connecting to the database.
driver_options: Other options for connecting to the database.
Then we will directly use an example to explain how to connect to the MySQL database through PDO. The specific code is as follows:
<?php
header("Content-Type:text/html; charset=utf-8"); //设置页面的编码格式
$dbms = "mysql"; // 数据库的类型
$dbName ="php_cn"; //使用的数据库名称
$user = "root"; //使用的数据库用户名
$pwd = "root"; //使用的数据库密码
$host = "localhost"; //使用的主机名称
$dsn = "$dbms:host=$host;dbName=$dbName ";
try{ //捕获异常
$pdo = new PDO($dsn,$user,$pwd); //实例化对象
echo "PDO连接数据库成功";
}catch (Exception $e){
echo $e->getMessage()."<br>";
}The output result of the page is as follows:
Note: If any of the above fields are filled in incorrectly, an exception will be thrown through the try catch statement!
DSN detailed explanation
What is DSN?
DSN is the abbreviation of Data Source Name. DSN provides the information needed to connect to the database. The DSN of PDO includes 3 parts: PDO driver name (such as: mysql, sqlite or pgsql), colon and driver-specific syntax. Each database has its own specific driver syntax.
When using different databases, it must be clear that the database server is completely independent from PHP and is an entity. However, in actual situations, the database server and the Web server may not be on the same computer. In this case, when you need to connect to the database through PDO, modify the host name in the DSN.
Because the database server only listens for connection requests on a specific port. Each database server has a default port number (MySQL is 3306), but the database administrator can modify the port number, so it is possible that PHP cannot find the port number of the database. In this case, the port number can be included in the DSN. For example:
$dsn="mysql:host=127.0.0.1;port=3306;dbname=admin";
Since there may be multiple databases in one database at the same time, when connecting to the database through DSN, the database name is usually included. This can ensure that the database that the user wants is connected, not other databases. Got it!
This is where we introduce the detailed explanation of using the PDO constructor to connect the database and DSN. You can test it locally. Then we will introduce to you several methods of executing SQL statements in PDO. For details, please Read "Three ways to execute SQL statements in PDO"!
The above is the detailed content of Detailed explanation of using PDO constructor to connect to database and DSN. 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
Solution to PHP Fatal error: Call to undefined method PDO::prepare() in
Jun 22, 2023 pm 06:40 PM
PHP is a popular web development language that has been used for a long time. The PDO (PHP Data Object) class integrated in PHP is a common way for us to interact with the database during the development of web applications. However, a problem that some PHP developers often encounter is that when using the PDO class to interact with the database, they receive an error like this: PHPFatalerror:CalltoundefinedmethodPDO::prep
How to use PHP's PDO_PGSQL extension?
Jun 02, 2023 pm 06:10 PM
As a popular programming language, PHP is widely used in the field of web development. Among them, PHP's PDO_PGSQL extension is a commonly used PHP extension. It provides an interactive interface with the PostgreSQL database and can realize data transmission and interaction between PHP and PostgreSQL. This article will introduce in detail how to use PHP's PDO_PGSQL extension. 1. What is the PDO_PGSQL extension? PDO_PGSQL is an extension library of PHP, which
PHP and PDO: How to perform bulk inserts and updates
Jul 28, 2023 pm 07:41 PM
PHP and PDO: How to perform batch inserts and updates Introduction: When using PHP to write database-related applications, you often encounter situations where you need to batch insert and update data. The traditional approach is to use loops to perform multiple database operations, but this method is inefficient. PHP's PDO (PHPDataObject) provides a more efficient way to perform batch insert and update operations. This article will introduce how to use PDO to implement batch insert and update operations. 1. Introduction to PDO: PDO is PH
PHP and PDO: How to perform paging queries and display data
Jul 29, 2023 pm 04:10 PM
PHP and PDO: How to query and display data in pages When developing web applications, querying and displaying data in pages is a very common requirement. Through paging, we can display a certain amount of data at a time, improving page loading speed and user experience. In PHP, the functions of paging query and display of data can be easily realized using the PHP Data Object (PDO) library. This article will introduce how to use PDO in PHP to query and display data by page, and provide corresponding code examples. 1. Create database and data tables
PHP PDO vs. mysqli: compare and contrast
Feb 19, 2024 pm 12:24 PM
PDOPDO is an object-oriented database access abstraction layer that provides a unified interface for PHP, allowing you to use the same code to interact with different databases (such as Mysql, postgresql, oracle). PDO hides the complexity of underlying database connections and simplifies database operations. Advantages and Disadvantages Advantages: Unified interface, supports multiple databases, simplifies database operations, reduces development difficulty, provides prepared statements, improves security, supports transaction processing Disadvantages: performance may be slightly lower than native extensions, relies on external libraries, may increase overhead, demo code uses PDO Connect to mysql database: $db=newPDO("mysql:host=localhost;dbnam
PHP and PDO: How to handle JSON data in a database
Jul 29, 2023 pm 05:17 PM
PHP and PDO: How to handle JSON data in databases In modern web development, processing and storing large amounts of data is a very important task. With the popularity of mobile applications and cloud computing, more and more data are stored in databases in JSON (JavaScript Object Notation) format. As a commonly used server-side language, PHP's PDO (PHPDataObject) extension provides a convenient way to process and operate databases. Book
PHP and PDO: How to perform a full-text search in a database
Jul 30, 2023 pm 04:33 PM
PHP and PDO: How to perform a full-text search in a database In modern web applications, the database is a very important component. Full-text search is a very useful feature when we need to search for specific information from large amounts of data. PHP and PDO (PHPDataObjects) provide a simple yet powerful way to perform full-text searches in databases. This article will introduce how to use PHP and PDO to implement full-text search, and provide some sample code to demonstrate the process. first
PHP and PDO: How to perform database backup and restore operations
Jul 29, 2023 pm 06:54 PM
PHP and PDO: How to perform database backup and restore operations When developing web applications, database backup and restore are very important tasks. As a popular server-side scripting language, PHP provides a wealth of libraries and extensions, among which PDO (PHP Data Objects) is a powerful database access abstraction layer. This article will introduce how to use PHP and PDO to perform database backup and restore operations. Step 1: Connect to the database Before actual operation, we need to establish a connection to the database. Use PDO pair
