PHP数据库函数实现数据的增删改查功能

<?php
$servername = "localhost";
$username = "root";
$passWord = "";
$dbname = "test_db";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("数据库连接失败: " . $conn->connect_error);
}
echo "数据库连接成功";
?>

<?php
$sql = "INSERT INTO users (name, email, password) VALUES ('John', 'john@example.com', 'password123')";

// 检查插入是否成功
if ($conn->query($sql) === TRUE) {
    echo "新记录插入成功";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}
?>

<?php
$sql = "SELECT * FROM users";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出每行数据
    while($row = $result->fetch_assoc()) {
        echo "姓名: " . $row["name"]. " - 邮箱: " . $row["email"]. " - 密码: " . $row["password"]. "<br>";
    }
} else {
    echo "0 结果";
}
?>

<?php
$sql = "UPDATE users SET email='john.doe@example.com' WHERE id=1";

if ($conn->query($sql) === TRUE) {
    echo "记录更新成功";
} else {
    echo "Error updating record: " . $conn->error;
}
?>

<?php
$sql = "DELETE FROM users WHERE id=1";

if ($conn->query($sql) === TRUE) {
    echo "记录删除成功";
} else {
    echo "Error deleting record: " . $conn->error;
}
?>