Hàm mysqli_field_tell() trong PHP - PHP Function

$con = mysqli_connect("localhost","my_user","my_password","my_db");
// Check connection
if (mysqli_connect_errno()){
	echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$sql="SELECT Lastname,Age FROM Persons ORDER BY Lastname";

if ($result=mysqli_query($con,$sql)){

  // Get field info for all fields
	while ($fieldinfo=mysqli_fetch_field($result)){
	    // Get field cursor position
	    $currentfield=mysqli_field_tell($result);
	    
	    printf("Column %d:
", $currentfield);
	    printf("Name: %s
", $fieldinfo->name);
	    printf("Table: %s
", $fieldinfo->table);
	}
	// Free result set
	mysqli_free_result($result);
}

mysqli_close($con);