php操作mysql_PHP

PHP操作MySQL

在Web开发中，PHP和MySQL是一对常见的组合，PHP是一种服务器端的脚本语言，而MySQL则是一种关系型数据库管理系统，通过PHP操作MySQL，可以实现动态网站的开发，本文将介绍如何使用PHP来操作MySQL数据库。

连接MySQL数据库

要使用PHP操作MySQL，首先需要连接到MySQL数据库，可以使用mysqli扩展或者PDO扩展来实现。

1、使用mysqli扩展连接MySQL

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检查连接
if ($conn>connect_error) {
    die("连接失败： " . $conn>connect_error);
} 
echo "连接成功";
?>

2、使用PDO扩展连接MySQL

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // 设置PDO错误模式为异常
    $conn>setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "连接成功"; 
} catch(PDOException $e) {
    echo "连接失败： " . $e>getMessage();
}
?>

执行SQL语句

连接成功后，就可以执行SQL语句了，可以使用mysqli或PDO的API来执行SQL语句。

1、使用mysqli执行SQL语句

<?php
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn>query($sql);
if ($result>num_rows > 0) {
    // 输出数据
    while($row = $result>fetch_assoc()) {
        echo "id: " . $row["id"]. " Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 结果";
}
$conn>close();
?>

2、使用PDO执行SQL语句

<?php
$sql = "SELECT id, firstname, lastname FROM MyGuests";
foreach ($conn>query($sql) as $row) {
    echo $row['id'] . "t" . $row['firstname'] . "t" . $row['lastname'] . "<br>";
}
$conn = null;
?>

插入、更新和删除数据

除了查询数据外，还可以使用PHP操作MySQL进行插入、更新和删除数据的操作。

1、插入数据

<?php
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";
if ($conn>query($sql) === TRUE) {
    echo "新记录插入成功";
} else {
    echo "Error: " . $sql . "<br>" . $conn>error;
}
$conn>close();
?>

2、更新数据

<?php
$sql = "UPDATE MyGuests SET lastname='Doe' WHERE id=2";
if ($conn>query($sql) === TRUE) {
    echo "记录更新成功";
} else {
    echo "Error updating record: " . $conn>error;
}
$conn>close();
?>

3、删除数据

<?php
$sql = "DELETE FROM MyGuests WHERE id=1";
if ($conn>query($sql) === TRUE) {
    echo "记录删除成功";
} else {
    echo "Error deleting record: " . $conn>error;
}
$conn>close();
?>

预处理语句

为了提高安全性和性能，可以使用预处理语句，预处理语句可以防止SQL注入攻击，并且可以提高数据库性能。

1、使用mysqli预处理语句

<?php
$stmt = $conn>prepare("INSERT INTO MyGuests (firstname, lastname, email) VALUES (?, ?, ?)");
$stmt>bind_param("sss", $firstname, $lastname, $email);
$firstname = "John";
$lastname = "Doe";
$email = "john@example.com";
$stmt>execute();
echo "新记录插入成功";
$stmt>close();
$conn>close();
?>

2、使用PDO预处理语句

<?php
$stmt = $conn>prepare("INSERT INTO MyGuests (firstname, lastname, email) VALUES (:firstname, :lastname, :email)");
$stmt>bindParam(':firstname', $firstname);
$stmt>bindParam(':lastname', $lastname);
$stmt>bindParam(':email', $email);
$firstname = "John";
$lastname = "Doe";
$email = "john@example.com";
$stmt>execute();
echo "新记录插入成功";
$conn = null;
?>