php对Mysql基本编程_mysql的应用编程php

1、建立PHP工程
2、分别定义MYSQL数据库的IP地址、用户名、用户密码、数据库名
$servername = “localhost”;
$username = "username ";
$password = "password ";
$dbname = “mysql”;
3、用方法mysqli_connect实例化mysqli
4、用mysqli的query方法查询数据集
5、用数据集的fetch_assoc()方法遍历数据集

<?php
$servername = "localhost";
$username = "username ";
$password = "password ";
$dbname = "mysql";

try {    
    // 对mysqli类进行实例化
    $conn = mysqli_connect($servername, $username, $password, $dbname);
    if (mysqli_connect_errno()) { // 判断是否成功连接上MySQL数据库
        throw new Exception('数据库连接错误！'); // 如果连接错误，则抛出异常
    } else {
        echo '数据库连接成功！'; // 打印连接成功的提示
        echo "<br>";
    }
} catch (Exception $e) { // 捕获异常
    echo $e->getMessage(); // 打印异常信息
}

$sql = "SELECT host, user FROM user";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出数据
    while ($row = $result->fetch_assoc()) {
        echo "host: " . $row["host"] . " - user: " . $row["user"];
        echo "<br>";
    }
} else {
    echo "0 结果";
}
$conn->close();
?>
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