Hàm mysqli_field_seek() 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,$sql)){
	// Get field info for 1st column ("Lastname")
	mysqli_field_seek($result,0);
	$fieldinfo = mysqli_fetch_field($result);

	printf("Name: %s
",$fieldinfo->name);
	printf("Table: %s
",$fieldinfo->table);
	printf("max. Len: %d
",$fieldinfo->max_length);

	// Free result set
	mysqli_free_result($result);
}

mysqli_close($con);