


How to use PHP to perform database search and modification operations
In web development, the database is an integral part. PHP, as a popular web programming language, integrates very well with various database systems. In PHP, MySQL is one of the most commonly used relational database systems.
In PHP, database operations are usually divided into two categories: search and modification. The search operation refers to obtaining data from the database and displaying it, while the modification operation refers to adding, deleting, modifying and other operations to the data in the database. This article will introduce how to use PHP to perform database search and modification operations.
1. Database connection
Before performing database operations, we need to connect to the database first. In PHP, you can use mysqli and PDO to implement database connections and operations. This article introduces the mysqli connection method.
To connect to the MySQL database, we need to define the host name, user name and password required to access the database, as well as the name of the database to be accessed. The following is a sample code for connecting to a MySQL database:
$servername = "localhost"; $username = "username"; $password = "password"; $dbname = "myDB"; // 创建连接 $conn = new mysqli($servername, $username, $password, $dbname); // 检查连接是否成功 if ($conn->connect_error) { die("连接失败: " . $conn->connect_error); } echo "连接成功";
2. Database search operation
The common ways to perform database search operations are as follows:
- Use the SELECT statement to query data
The SELECT statement is the most commonly used query statement. It can get data from one or more tables and filter based on conditions. The following is a sample code for using the SELECT statement to query data:
$sql = "SELECT id, name, email FROM users"; $result = $conn->query($sql); if ($result->num_rows > 0) { // 输出数据 while($row = $result->fetch_assoc()) { echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>"; } } else { echo "0 结果"; }
- Querying data using the WHERE clause
The WHERE clause is used to filter data that meets specified conditions. The following is a sample code for querying data using the WHERE clause:
$sql = "SELECT id, name, email FROM users WHERE name='John'"; $result = $conn->query($sql); if ($result->num_rows > 0) { // 输出数据 while($row = $result->fetch_assoc()) { echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>"; } } else { echo "0 结果"; }
- Querying data using LIKE
The LIKE operator is used for fuzzy matching in the WHERE clause. The following is a sample code for using LIKE to query data:
$sql = "SELECT id, name, email FROM users WHERE name LIKE '%John%'"; $result = $conn->query($sql); if ($result->num_rows > 0) { // 输出数据 while($row = $result->fetch_assoc()) { echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>"; } } else { echo "0 结果"; }
3. Database modification operations
The common ways to perform database modification operations are as follows:
- Insert data using the INSERT statement
The INSERT statement is used to insert data into the database. The following is a sample code to insert data using the INSERT statement:
$sql = "INSERT INTO users (name, email, password) VALUES ('John', 'john@example.com', '12345')"; if ($conn->query($sql) === TRUE) { echo "新纪录插入成功"; } else { echo "Error: " . $sql . "<br>" . $conn->error; }
- Update data using the UPDATE statement
The UPDATE statement is used to update data in the database. The following is a sample code for updating data using UPDATE statement:
$sql = "UPDATE users SET email='john@example.com' WHERE name='John'"; if ($conn->query($sql) === TRUE) { echo "数据更新成功"; } else { echo "Error updating record: " . $conn->error; }
- Deleting data using DELETE statement
DELETE statement is used to delete data from the database. The following is a sample code for using the DELETE statement to delete data:
$sql = "DELETE FROM users WHERE name='John'"; if ($conn->query($sql) === TRUE) { echo "数据删除成功"; } else { echo "Error deleting record: " . $conn->error; }
IV. Summary
This article introduces common ways to use PHP to perform database search and modification operations, including using SELECT statement to query data, use WHERE clause to query data, use LIKE to query data, use INSERT statement to insert data, use UPDATE statement to update data and use DELETE statement to delete data. Mastering these skills will make you better at web development using PHP and MySQL.
The above is the detailed content of How to use PHP to perform database search and modification operations. 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

AI Hentai Generator
Generate AI Hentai for free.

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

In this chapter, we will understand the Environment Variables, General Configuration, Database Configuration and Email Configuration in CakePHP.

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

To work with date and time in cakephp4, we are going to make use of the available FrozenTime class.

To work on file upload we are going to use the form helper. Here, is an example for file upload.

In this chapter, we are going to learn the following topics related to routing ?

CakePHP is an open-source framework for PHP. It is intended to make developing, deploying and maintaining applications much easier. CakePHP is based on a MVC-like architecture that is both powerful and easy to grasp. Models, Views, and Controllers gu

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

Validator can be created by adding the following two lines in the controller.
