What are the differences between mysqli_error() and mysql_error() functions in PHP and how should they be used?

The main difference between mysqli_error() and mysql_error() functions in PHP is that mysqli_error() is used with the improved MySQLi extension, while mysql_error() is used with the deprecated MySQL extension. It is recommended to use mysqli_error() as it supports more features and is more secure. To fix any errors related to database queries, always use mysqli_error() with the MySQLi extension.

// Using mysqli_error() to handle errors with the MySQLi extension
$con = mysqli_connect("localhost", "username", "password", "database");

if (mysqli_connect_errno()) {
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$query = "SELECT * FROM table";
$result = mysqli_query($con, $query);

if (!$result) {
    echo "Error: " . mysqli_error($con);
}

// Close the connection
mysqli_close($con);