Truncate does not work

[Gordon White]

I have the following code that does not work.
I followed all of the examples I found and still nothing.

<?PHP
include "config.php";

$sql = "TRUNCATE TABLE data1";
$sql.= "TRUNCATE TABLE data2";
$sql.= "TRUNCATE TABLE data3";
$sql.= "TRUNCATE TABLE data4";
$$result = mysqli_query($sql,$conn);

All of my INSERT statements following these do work.

I know it may be simple for you guys but I'm stuck.

Thanks