php之sql语句 创建数据库、表、插入字段，自动判断是否成功

<?php
header("content-type:text/html;charset=utf-8");         //设置编码
$servername = "localhost";
$username = "root";
$password = "";
$db = "";
// 创建连接
$conn = new mysqli($servername, $username, $password);
// 检测连接
if ($conn->connect_error) {
    die("连接失败: " . "<br>" . $conn->connect_error);
}
// 创建数据库
$sql = "Create Database If Not Exists MyDB Character Set UTF8";
if ($conn->query($sql) === TRUE) {
    echo "创建数据库成功" . "<br>";
    $conn->query("use myDB");
    $sql = "CREATE TABLE If Not Exists imgs (
        imgUrl VARCHAR(200) NOT NULL,
        reg_date TIMESTAMP
        )";

    if (mysqli_query($conn, $sql)) {
        echo "数据表 imgs 创建成功" . "<br>";
        $sql = "INSERT INTO imgs (imgUrl) VALUES ('" . $_POST["img"] . "')";

        if ($conn->query($sql) === TRUE) {
            echo "新记录插入成功" . "<br>";
        } else {
            echo "Error: " . $sql . "<br>" . $conn->error;
        }
    } else {
        echo "创建数据表错误: " . "<br>" . mysqli_error($conn);
    }
} else {
    echo "Error creating database: " . "<br>" . $conn->error;
}
?>