How to use MySQL delete statement in PHP

MySQL is an open source relational database system that is often used for Web applications to store and retrieve data. Using MySQL in PHP, we can operate various database operations, including inserting, updating, and deleting data. This article focuses on explaining how to use MySQL delete statements in PHP.

1. Overview of MySQL delete statement

The MySQL delete statement can be used to delete data in the database table. There are two main delete statements in MySQL: DELETE and TRUNCATE. Both statements can delete data in the table, but there are some slight differences in operation. We need to choose to use them according to the specific situation.

1. DELETE statement

The DELETE statement is used to delete data that meets specified conditions in the table. The syntax is as follows:

DELETE FROM table_name WHERE condition;

Among them, table_name represents the name of the table to delete data, condition is the specified condition.

2. TRUNCATE statement

The TRUNCATE statement is used to delete all data in the table. The syntax is as follows:

TRUNCATE TABLE table_name;

Among them, table_name Indicates the name of the table whose data is to be deleted.

2. Using the MySQL delete statement in PHP

To use the MySQL delete statement in PHP, you need to use the MySQLi extension or PDO extension to connect to the database and perform operations. The following describes how to use MySQL delete statements using MySQLi and PDO extensions.

1. Using the MySQLi extension

When using the MySQLi extension, you first need to create an object that connects to the MySQL server, and then use the object to execute MySQL queries.

<?php
// 创建连接
$conn = mysqli_connect("localhost", "username", "password", "mydb");

// 检查连接
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// 删除数据
$sql = "DELETE FROM users WHERE name=&#39;John&#39;";

if (mysqli_query($conn, $sql)) {
    echo "Record deleted successfully";
} else {
    echo "Error deleting record: " . mysqli_error($conn);
}

// 关闭连接
mysqli_close($conn);
?>

2. Using PDO extension

When using PDO extension, you need to create a PDO object, which can be connected to different database types and support different types of queries. efficiency.

<?php
try {
    // 创建连接
    $conn = new PDO("mysql:host=localhost;dbname=mydb", "username", "password");

    // 设置PDO错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 删除数据
    $sql = "DELETE FROM users WHERE name='John'";
    $conn->exec($sql);

    echo "Record deleted successfully";
} catch(PDOException $e) {
    echo $sql . "<br>" . $e->getMessage();
}

// 关闭连接
$conn = null;
?>

Summary

This article mainly introduces the use of MySQL delete statements in PHP, including the syntax and usage of DELETE and TRUNCATE statements. By studying this article, readers can learn how to use MySQLi and PDO extensions to connect to the database and perform deletion operations. Of course, the actual situation requires you to choose whether to apply the delete statement according to specific needs.

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