phpcms数据库报错

Error: Could not connect to database

// 示例代码：连接数据库
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "your_dbname";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";

Error: You have an error in your SQL syntax

// 示例代码：执行SQL查询
$sql = "SELECT id, name FROM users WHERE age > 25";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }
} else {
    echo "0 results";
}

Error: Access denied for user

-- 示例代码：授予权限
GRANT SELECT, INSERT, UPDATE, DELETE ON your_dbname.* TO 'your_username'@'localhost';
FLUSH PRIVILEGES;